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Grade levels: 5-8, 9-12
Theme: water cycle
Tool: http://aquarius.nasa.gov/education-datatools.html

Analyzing sea surface salinity data patterns over time provides insight into variations in the earth's water cycle. This is because some water cycle processes increase salinity while other processes decrease salinity (see map at right).

Salinity patterns are governed by geographic differences in the "water budget." For example, like on continents, some areas of the ocean are rainy whereas others are arid and "desert-like." To learn more about the factors that influence salinity patterns, we invite you investigate five pairs of data maps centered over the North Atlantic Ocean (listed below). Each map shows monthly conditions based on long-term averages. The challenge is to find the data set that most closely corresponds to sea surface salinity patterns.

Grade level 5-8: Look at monthly maps of: air temperature vs. sea surface salinity and precipitation vs. sea surface salinity. Are any of these data sets closely correlated with solar energy input (e.g., seasonal change)?

Grade level 9-12: For the North Atlantic Ocean, look at monthly maps of air temperature vs. sea surface salinity and precipitation vs. sea surface salinity and evaporation vs. sea surface salinity. Are changes in these data sets closely correlated with solar energy input (e.g., seasonal change) in the North Atlantic ocean? Look at these videos -- Sea Surface Salinity and Components of the Water Cycle for global data sets of sea surface temperature, precipitation, and evaporation.

Grade levels: K-4, 5-8, 9-12
Themes: 21st century technology, ocean circulation, water cycle
Flat Tool: http://ourocean.jpl.nasa.gov/AQUARIUS/chp2.jsp
GoogleEarth Interface Tool: http://aquarius.jpl.nasa.gov/AQUARIUS_DEV/chp2.jsp

Create global maps of mean conditions for any month at designated depths (down to 1500m) using the pull-down menus. Monthly time-series graphs of salinity, temperature, or density can be plotted by selecting up to six locations (by clicking on the map or typing latitude/latitude information into the fields below). These time-series graphs can also represent up to six different depths. Plotted data will also be shown in a table that is easily downloaded (e.g., into Excel). Sources include interpolated atlas data or actual measurements from the database.

Focus Questions | Flat Tool Tutorial

Grade level: K-4
Theme: water cycle
Activity: http://aquarius.nasa.gov/sea_water_freeze.html

Big Idea

Key Concepts

Background
Under normal conditions, ordinary fresh water freezes and melts at 0°C, or 32°F. If water and ice are at 0°C, which is the melting point of ice and the freezing point of water then molecules of ice are escaping into the water (melting), and molecules of water are being captured on the surface of the ice (freezing). (more)

Grade levels: 5-8, 9-12
Themes: 21st century technology, climate, water cycle
Flat Tool: http://ourocean.jpl.nasa.gov/AQUARIUS/chp3.jsp
GoogleEarth Interface Tool: http://aquarius.jpl.nasa.gov/AQUARIUS_DEV/chp3.jsp

Create global maps of mean conditions for any year(s) from 1800 to 2005 at designated depths (down to 1500m) using the pull-down menus. Annual time-series graphs of salinity, temperature, or density can be plotted by selecting up to six locations (by clicking on the map or typing latitude/latitude information into the fields below). These time-series graphs can also represent up to six different depths. Plotted data will also be shown in a table that is easily downloaded (e.g., into Excel). Source is actual, non-interpolated database measurements.

Focus Questions | Flat Tool Tutorial

Grade level: 9-12
Theme: water cycle
Video: global_ocean_04.flv

Soon a new satellite will even help us see tiny particles on the ocean's surface - like salt, which drives huge conveyor belts of water through the world's oceans, connecting currents and moving heat from pole to pole. Climate change could mean big changes for oceans. And that in turn would make life very different for those of us on dry land.

Paula Bontempi: "If the climate actually changes, and the oceans change or respond to that change, it most definitely will impact life as we know it, and especially humans."

David Adamec: "To understand exactly how we stay here and how we're going to survive both within the climate, and even our life cycle, it requires understanding what the water is doing."

Our climate is changing... in some places, faster than predicted. By using science to understand those changes, we can find ways of protecting our oceans - and ourselves - that make a world of difference.

Grade level: 9-12
Theme: water cycle
Video: global_ocean_03.flv

Other kinds of satellite sensors look at the Earth in a far different light. Heat sensing satellite instruments take the Earth's temperature by measuring infrared energy. Infrared wavelengths are invisible to our eyes, but some satellites can see them. And, as our climate changes, we can see ocean temperatures on the rise.

Other satellites show us peaks and valleys, not just on land - but, believe it or not - on the surface of the ocean. And as ice on land melts, there are increasingly more highs than lows. Sea level is rising.

Grade level: 9-12
Theme: water cycle
Activity: http://www.tos.org/hands-on/teaching_phys_concepts.pdf

Activity 1.6: Convection Under Ice (p. 10). In oceanography, density is used to characterize and follow water masses as a means to study ocean circulation. Many processes are caused by or reflect differences in the densities of adjacent water masses or differences in densities between fluids and solids. Plate tectonics and ocean basin formation, deep-water formation and thermohaline circulation, and carbon transport by particles sinking from surface waters to depth are a few examples of density-driven processes. This activity is designed to highlight links to oceanic processes.

In the left panel in the photo at right, an ice block floats in tap water because the density of ice is lower than that of freshwater. As the ice melts, however, cold, colored meltwater sinks to the bottom because it is denser than the tap water. Warmer water from the bottom is then displaced and upwells, resulting in a convective flow visible in the dye patterns. Ice melting in the center of the tank is analogous to a convection "chimney" formed in the open ocean, while ice melting at the tank's edge is analogous to a chimney on a continental shelf (near a land mass). Such chimneys in the ocean, created and sustained by convective processes, appear as "columns" of mixed water that flow downwards. For a given set of oceanic and meteorological conditions, open-water convection tends to entrain (mix with) more of the surrounding waters than does convection near a land mass. The open-ocean case therefore results in downwelled water that is less dense.

In the right panel, the ice block floats in dense, salty water. As the ice melts, only a small amount of dye sinks because the density of the saltwater is greater than the density of the newly melted, fresh, ice-cold water. Most of the meltwater accumulates in a surface layer on top of the denser salt layer.

Read the Background section (p. 4-5) of Chapter 1 (Density) in preparation for this activity.

Note: Even though this experiment focuses on temperature only, it can be used to discuss how salinity, like temperature, affects the density of ocean water.

Grade level: 9-12
Theme: water cycle
Activity: http://www.tos.org/hands-on/teaching_phys_concepts.pdf

Activity 1.5: Effect of Stratification on Mixing (p. 9-10). In open ocean regions (with the exception of polar seas), the water column is generally characterized by three distinct layers: an upper mixed layer (a layer of warm, less-dense water with temperature constant as a function of depth), the thermocline (a region in which the temperature decreases and density increases rapidly with increasing depth), and a deep zone of dense, colder water in which density increases slowly with depth.

Mixing of stratified layers requires work. Without energetic mixing (e.g., due to wind or breaking waves), the exchanges of gases and nutrients between surface and deep layers will occur by molecular diffusion and local stirring by organisms, which are slow, ineffective modes of transfer. The energy needed for mixing is, at a minimum, the difference in potential energy between the mixed and stratified fluids. Therefore, the more stratified the water column, the higher the energy needed for vertical mixing.

Density is fundamentally important to large-scale ocean circulation. An increase in the density of surface water, through a decrease in temperature (cooling) or an increase in salinity (ice formation and evaporation), results in gravitational instability (i.e., dense water overlying less-dense water) and sinking of surface waters to depth. Once a sinking water mass reaches a depth at which its density matches the ambient density, the mass flows horizontally, along "surfaces" of equal density. This process of dense-water formation and subsequent sinking is the driver of thermohaline circulation in the ocean. It is observed in low latitudes (e.g., the Gulf of Aqaba in the Red Sea, the Gulf of Lions in the Mediterranean Sea) as well as in high latitudes (e.g., deep water formation in the North Atlantic).

This experiment looks at the energy required to mix two layers. Students should read the Background section (p. 4-5) of Chapter 1 (Density) in preparation for this activity.

Flash Video | QuickTime Movie

Grade level: K-4
Theme: water cycle
Activity: http://aquarius.nasa.gov/evap_invest.html

Big Idea

Key Concepts

Background
Evaporation is the process by which water changes from a liquid to a gas or vapor. Evaporation is the primary pathway that water moves from the liquid state back into the water cycle as atmospheric water vapor. Studies have shown that the oceans, seas, lakes, and rivers provide nearly 90 percent of the moisture in the atmosphere via evaporation, with the remaining 10 percent being contributed by plant transpiration.

Grade level: K-4
Theme: water cycle
Video: salty_regions.flv

Very salty parts of the world's ocean are the Mediterranean Sea and also the Red Sea. In fact, those areas are some of the saltiest places we know in the global ocean. The reason they are so salty is that there is such strong evaporation because they're so warm there and they have high winds. So those places are very salty.

And also in the middle of our subtropical gyres. A gyre is a current system that moves around in a circle. The "subtropics" means that it is located in an area around 30 degrees (north) latitude all around the globe. That area is where we have very strong evaporation. That evaporation means that we lose fresh water from the surface. And we lose more fresh water from the surface than we actually gain through precipitation. That area is what we call "the ocean deserts".

Now on the fresh side, we have very fresh water near the coastlines and that's because we have the river waters flowing in. And we also have fresh water near the high latitudes where we have ice.

Grade level: 5-8
Theme: water cycle
Activity: http://www.tos.org/hands-on/teaching_phys_concepts.pdf

Activity 4.5: Heat Flow and Latent Heat (p. 37-38). A good grasp of the underlying principles of thermal physics is essential for understanding how the ocean functions and how it impacts climate. Thermal physics is one of the science subjects that students are familiar with and experience on a daily basis, but intertwined with the experiential knowledge they bring to class comes a mixed bag of misconceptions that must be identified and addressed. Example misconceptions include an inability to differentiate between heat and temperature, the notion that transfer of heat will always result in a temperature rise, and a misunderstanding of latent heat. The purpose of this activity is to review basic concepts of thermal physics and highlight applications to ocean processes by focusing on the concept of latent heat.

When an object gains heat, two things can happen: the temperature of the object can rise, or the object can change its state without a measurable change in temperature (e.g., ice melting into water). Most materials have two state transitions: from solid to liquid and from liquid to gas. The heat needed to change the state of a material is called latent heat of fusion (for changing from solid to liquid) and latent heat of vaporization (for changing from liquid to gas). Latent heats of fusion and vaporization for water are high and have many important consequences for Earth's climate.

Flash Video | QuickTime Movie

Grade level: 5-8
Theme: water cycle
Video: hurricane_cloud_growth.flv

This animation depicts the hurricane cloud growth process. The release of latent heat (shown by orange "blobs") warms the surrounding air, making it lighter, which promotes updrafts (shown as blue arrows) and vigorous cloud development.

NASA's Tropical Rainfall Measuring Mission (TRMM) provides a closer look at hurricanes using a unique combination of passive and active microwave instruments designed to peer inside cloud systems and measure rainfall. TRMM allows scientists to study the combustion process in the hurricane engine and relate this process to intensification or weakening. (source)

Grade level: 5-8
Theme: water cycle
Video: hurricane_latent_heat.flv

This animation depicts the hurricane energy process. As water vapor is evaporated from the warm ocean surface, it is forced upward in towering convective clouds in the eyewall and rain band regions of the storm. As the water vapor changes from a gas to a liquid (cloud water), latent heat is released (shown by orange "blobs"). Red arrows show areas of low atmospheric pressure.

NASA's Tropical Rainfall Measuring Mission (TRMM) provides a closer look at hurricanes using a unique combination of passive and active microwave instruments designed to peer inside cloud systems and measure rainfall. TRMM allows scientists to study the combustion process in the hurricane engine and relate this process to intensification or weakening. (source)

Grade level: 5-8
Theme: water cycle
Video: hurricane_heat_engine.flv

This animation depicts the hurricane heat energy process. As water vapor is evaporated from the warm ocean surface, it is forced upward in towering convective clouds in the eyewall and rain band regions of the storm. As the water vapor changes from a gas to a liquid (cloud water), latent heat is released (shown by orange "blobs").

The release of latent heat warms the surrounding air, making it lighter, which promotes updrafts (shown as blue arrows) and vigorous cloud development.

Red arrows show areas of low atmospheric pressure. It is suspected that rapid bursts of cloud growth, particularly in the eyewall region of hurricanes, may relate to the intensification phase of a storm. (source)

Read Prerequisite Knowledge (p. 2-4).

Grade level: 5-8
Theme: water cycle
Activity: http://www.nasa.gov/pdf/62319main_ICS_Energy.pdf

Water is a key element of the Earth's energy balance. The Sun's energy drives the water cycle, and in turn, water is a major factor in governing the surface temperature of the Earth.

Read the section on Prerequisite Knowledge (p. 2-4).

Grade level: 9-12
Themes: climate, water cycle
Video: keeping_up_carbon_03.flv

At the most basic level, the balance between incoming sunlight and outgoing heat determines Earth's climate. Greenhouse gases act like a blanket, and trap heat in the atmosphere. Carbon dioxide is a greenhouse gas. In the past two centuries, humans have increased atmospheric carbon dioxide by more than 30%, by burning fossil-fuels and cutting down forests. The Earth has not experienced carbon dioxide levels this high for the past several million years.

Researchers are learning that future climate change will depend on carbon levels in the land, in the atmosphere, and in the sea, and how these levels respond to human disturbance. About one-third of all human-generated carbon emissions has dissolved into the ocean. More than 80% of Earth's added heat is now stored in the ocean.

Scott Doney: "In the future, as the planet gets warmer, the water's going to warm up, and warm water can hold less carbon than cold water - the other thing is, on a warmer planet, some of the currents are going to slow down, so we might not be forming as much of this cold deep water. So we won't be able to transport carbon into the deep sea. So on the whole, the ocean's going to become less effective at removing carbon from the atmosphere." (source)

Grade level: 9-12
Themes: climate, water cycle
Video: keeping_up_carbon_04.flv

Throughout most of Earth's ocean, the warmer water, weaker circulation, and new temperature gradients that result from climate change will impact marine life and ecosystems. These changes affect the ocean's ability to store carbon. Increased carbon dioxide in the atmosphere impacts marine life in other ways.

Stacey Boland: "As the ocean absorbs more carbon dioxide, it becomes more acidic, and this can be a threat to some of the organisms that live inside the ocean."

As Earth's climate continues to change, how will researchers monitor something as big as the ocean, and something as complex as the carbon cycle? NASA Earth observing satellites give scientists the "big picture" view of our home planet. Varied satellites help researchers detect changes in ocean climate and ecology over time, providing vital insight into the health of our home planet. (source)

Grade level: K-4
Theme: water cycle
Activity: http://aquarius.nasa.gov/liquid_rainbow.html

Big Idea

Key Concepts

Background
Density is a property of matter that can be introduced at the elementary level by thinking of it in terms of the relationship between weight and volume. How can two objects that are the same size have different weights? The answer has to do with their density. An object's density is determined by comparing its mass to its volume. If you compare a rock and a cork that are the same size (they have equal volume), which is heavier? The rock is, because it has more mass. Thus the rock is denser than the cork because it has more mass in the same volume.

Grade level: 9-12
Themes: climate, ocean circulation, water cycle
Video: melting_ice_03.flv

Two thirds of the fresh water on Earth is frozen in the world's ice fields. If that ice melts, seas will rise. If all of that ice were to melt, sea level would rise worldwide by 70 meters. No one expects all of that ice to melt anytime soon, but even the meter of sea level rise that many scientists predict for the next century could have dramatic consequences.

Lora Koenig: "Even though the polar regions seem very far from a lot of people's day to day life, they are very important. Because they are regions that cool our earth. And as they change, they're going to cause larger changes throughout the rest of the globe." (source)

Grade level: 9-12
Themes: climate, ocean circulation, water cycle
Video: melting_ice_02.flv

It's important to understand how the world's ice sheets form, how they change over time, and how fast they are moving into the sea. That's where researchers like NASA's Lora Koenig come in. She recently spent three months in Greenland studying the composition of those ice sheets. All ice sheets and glaciers start as snowfall. Those tiny flakes get compressed by the weight of more snow above, and eventually become dense masses of ice.

Lora Koenig: "What we're seeing right now on the ice sheets and glaciers is that they are shrinking in size. And as glaciers on land are shrinking overall, that contributes a little bit to sea level rise. And we are worried that as we see warming over the ice sheets, and increased melting over the ice sheets, that they are going to start contributing much more to sea level rise." (source)

Grade level: 9-12
Themes: climate, ocean circulation, water cycle
Video: melting_ice_04.flv

Josh Willis: "A lot of people live in coastal areas. Coastal places that have beaches. As sea level rises, then beaches begin to erode and we begin to lose wetlands. A lot of different ecologically-sensitive regions lie along the coastline, and as sea level rises, these get flooded (and) the ecosystems, of course, change. And so all of this can have big consequences for people and especially people who live near the coast."

Josh Willis: "As the great ice sheets in Antarctica and Greenland begin to melt and break up due to global warming, we really might experience very rapid sea level rise; three or four times as fast as the rate that we see today. So predicting this rate out into the future is very tricky because we really don't know when the ice sheets might break up and how fast they will when they do. So predicting future sea level rise is one of the great scientific problems of the future." (source)

Grade level: 9-12
Themes: climate, ocean circulation, water cycle
Video: melting_ice_01.flv

The ice is melting. The seas are rising. Little by little, in most parts of the world, the ocean is overtaking the land. Most of us don't think much about sea level rise, but it's one of the biggest signs that humans are affecting the Earth's climate. And it's something worth watching. So the big question is, are we facing a doom and gloom scenario?

Josh Willis: "I prefer not to think about climate change and global warming in terms of doom and gloom scenarios, so much as a change in our planet. Our planet's definitely changing, and we're definitely causing it. So we're going to have learn to deal with some of these changes. But in addition, we're going to have to learn how to make a slightly smaller footprint on our planet."

Josh Willis: "Sea level is rising effectively because of global warming. As the planet heats up, two things happen to the ocean. One is that the temperature of the water increases. And as that happens, the water actually expands and takes up more room. The other thing that happens is that ice that was on land in the form of glaciers and ice sheets begins to melt and as that runs off into the ocean, it increases the water in the ocean, and it actually raises sea level as well. (source)

Grade level: K-4
Theme: water cycle
Activity: http://aquarius.nasa.gov/prop_fresh_sea.html

Big Idea

Key Concepts

Background
Liquid water (H2O) is often perceived to be pretty ordinary as it is transparent, odorless, tasteless and ubiquitous. Water is unique in that it is the only natural substance that is found in all three states -- liquid, solid (ice), and gas (steam) - at the temperatures normally found on Earth. Earth's water is constantly interacting, changing, and in movement. Water freezes at 32° Fahrenheit (F) and boils at 212° F (at sea level). In fact, water's freezing and boiling points are the baseline with which temperature is measured: 0° on the Celsius scale is water's freezing point, and 100° is water's boiling point. Water is unusual in that the solid form, ice, is less dense than the liquid form, which is why ice floats.

Grade level: 9-12
Theme: water cycle
Activity: http://www.tos.org/hands-on/teaching_phys_concepts.pdf

Activity 4.8: Reversing Rods (p. 40-41). Most substances expand when heated and contract when cooled. As the temperature of most substances increases, their molecules vibrate faster and move farther apart, occupying a larger space. When these substances are cooled, their molecules vibrate slower and remain closer to each other. Note that freshwater below 4°C actually expands when cooled, a phenomena known as the anomaly of water.

Thermal expansion is the principle by which a liquid thermometer works. In the ocean, thermal expansion is thought to contribute significantly to sea level rise on decadal-to-century-long time scales. However, thermal effects appear to be influenced by decadal climate-related fluctuations, making it difficult to estimate the long-term contribution of thermal expansion to sea level rise. Current estimates suggest that thermal expansion is responsible for 25 percent to 50 perccent of observed sea level rise.

In this activity, we look at thermal expansion using two rods, one made of aluminum and the other made of PVC. When placed in cold water, both rods initially float because their densities are lower than that of the cold water. Over time, the PVC rod gets colder and contracts, which results in a density change. When the density of the rod exceeds that of the water, the PVC sinks. The aluminum rod gets colder too, but aluminum expands and contracts much less than PVC when its temperature is changed by the same amount; therefore, the aluminum rod's density is less affected by the temperature change, and it remains floating. Students will also try this experiment with hot water.

Flash Video | QuickTime Movie

Grade level: 9-12
Theme: water cycle
Article: documents/21.1_schmitt.pdf

Articles in this salinity-themed Oceanography issue articulate the potential of our rapidly expanding ability to measure salinity to enhance understanding of the global water cycle.

Read and discuss the first three sections (p. 12-15) of this article.

Grade level: 9-12
Theme: water cycle
Video: salt_of_earth_04.flv

People have been measuring salinity for centuries, but ships and buoys alone cannot match the perspective from space. In fact, a whole quarter of the oceans have no salinity data at all.

Susan Lozier: "Up until now when we've been trying to understand how density changes impact ocean circulation, we've really just had half the picture."

When the Aquarius / SAC-D satellite is launched, scientists can look at salinity of the surface of the ocean from 400 miles above the earth.

Susan Lozier: "But now with the Aquarius mission, we'll be able to complete that other half. We'll be able to look at the salinity information. And so salinity, combined with temperature, will give us the information about the density field."

The satellite will gather more salinity data than in the last 125 years. This mission will help scientists better understand how salinity and ocean circulation are tied to global climate and how both systems are changing throughout time. (source)

Grade levels: 5-8, 9-12
Themes: climate, ocean circulation, water cycle
Video: salt_of_earth_03.flv

The oceans are vast, covering 70 percent of our planet, and so it is no surprise that we still know only a little about this system, and how it will respond to change, and furthermore, create change.

Jeff Halverson: "Climate change on earth is complicated by the fact that the ocean moves much more slowly than the atmosphere. So you have warming in the atmosphere, warming in the ocean, but they're occurring at different speeds. So they're out of sync, and that makes predicting what's going to happen in the next hundred or two years very, very difficult."

Susan Lozier: "Now what we might expect happens, in a very simplistic sense, is that as the ocean warms, there's going to be more evaporation. And that more evaporation would would mean that oceans become saltier. But really it's not just that simple because there's also evaporation, precipitation, and the ice as well, and that's all wrapped up in the study of the hydrologic cycle." (source)

Grade levels: 5-8, 9-12
Themes: climate, ocean circulation, water cycle
Video: salt_of_earth_02.flv

Susan Lozier: "And the atmosphere and the ocean, both being fluids of the earth, really work together. We consider them sort of equal partners in the redistribution of this heat on the planet. So when those warm waters are returning, as they're moving up to the higher and higher latitudes then, they're releasing that heat to the atmosphere. Then the winds blow over the ocean, they pick up that heat and those winds over the Atlantic Ocean are moving from the North American continent to the European continent."

Jeff Halverson: "It takes perhaps a thousand years for the water to cycle through the deep ocean. So we say the oceans have a memory. They're like a tape recorder. Things that happen now will still be manifest hundreds of years in the future as that cold water moves through this giant circulation."

Susan Lozier: "So if there's any change to that overturning circulation, that means that Northern Europe and the British Isles would be robbed of that heat due to those waters that are returning to the high latitudes." (source)

Grade levels: 5-8, 9-12
Themes: ocean circulation, water cycle
Video: salt_of_earth_01.flv

Susan Lozier: "And it seems a little odd in a way because salt is really a molecule in the ocean water, but collectively, that salinity plays a role in the ocean circulation."

It's these differences in salinity that play a role in the processes that affect weather, climate, sea life, and the whole ocean system itself. And not all oceans have the same salinity. In fact, the North Atlantic Ocean tends to be the saltiest, much more than the Pacific.

Susan Lozier: "The salt in the ocean affects its density, just like the temperature affects its density, and the density, meaning the amount mass per volume, is going to then impact where the water goes as it circulates throughout the globe."

Jeff Halverson: "Differences in temperature and salt content of the water cause some areas of water to sink and some areas of water to rise. And so we tend to see the sinking water at the poles, the water rising back up at the equator, and if you connect the two together, what you have is an overturning that is deep in the ocean. It's like a big conveyor belt that operates in the ocean."

This overturning moves warm water from the tropics toward the poles, and cold water from the poles toward the tropics. In this way the overturning regulates earth's climate. (source)

Grade levels: 5-8, 9-12
Themes: ocean circulation, water cycle
Video: density_reverse_direction.flv

The average density of sea surface water can be calculated from the average sea surface temperature and salinity using the state equation for seawater. This animation shows the long term average sea surface density, with light blue regions having the least density and dark blue regions having the greatest density. The sea surface density variations are actually very small, less than 3 percent overall, but the variation is very important.

There are three stable, dense regions in the ocean's surface, one in the sea around Iceland, Greenland, and Scandinavia and the other two near or under major Antarctic ice shelves. In these regions, the surface water becomes dense enough to sink and join the deep ocean currents. In fact, this sinking is thought to drive these deep currents as part of a system called the Thermohaline Circulation. This circulation has a strong effect on the Earth's climate, influencing the Gulf Stream, El Niño events, and both past and future climate shifts. (source)

Grade level: 9-12
Theme: water cycle
Video: Aerosol_Sources_Full_Seq_640x360.flv

Aerosols are complex particles; they occur in nature and can also be generated by human activity. One important new area of aerosol research involves how aerosols impact clouds. Without aerosols, clouds could not exist. Aerosol particles serve as condensation nuclei for water vapor in the atmosphere. Atmospheric water molecules are drawn to aerosol particles like magnets, forming water droplets and eventually creating a cloud. The introduction of a larger number of aerosols will modify cloud's natural properties, leading to an accumulation of water droplets that are smaller in size but greater in number. Clouds play an important role in regulating Earth's climate; aerosol-rich air masses generate clouds that are bigger, brighter, and longer lasting.

Aerosols can occur in nature, but they can also originate from human activity. This animation provides an introduction to four of the varied sources of atmospheric aerosols: cities, forest fires, the ocean, and deserts. This animation shows the different sources of aerosols, how they mix in the Earths atmosphere, and finally disappear by creating sediment or raining out.

Of particular interest is the role of the oceans: salts from the sea spray serve as condensation nuclei. In this animation, sea salt spray aerosols rise into the sky, follows the path downwards to the source (the ocean), and back up into the sky where the aerosols gather in a cloud. (source)

Grade levels: 5-8, 9-12
Themes: 21st century technology, climate, ocean circulation, water cycle
Flat Tool: http://ourocean.jpl.nasa.gov/AQUARIUS/chp1.jsp
GoogleEarth Interface Tool: http://aquarius.jpl.nasa.gov/AQUARIUS_DEV/chp1.jsp

Interactive maps of surface conditions can be clicked to create in-water profiles of salinity, temperature, or density. Sources include interpolated atlas data or actual measurements from the database.

Focus Questions | Flat Tool Tutorial

Grade levels: K-4, 5-8, 9-12
Themes: ocean circulation, water cycle
Video: water_cycle_ipod_640x480.m4v.flv

This animation shows one molecule of water completing the hydrologic cycle. Heat from the sun causes the molecule to evaporate from the ocean's surface. Once it evaporates, it is transported high in the atmosphere and condenses to form clouds.

Clouds can move great distances and eventually the water molecule will fall as rain or snow. Ultimately, the water molecule arrives back where it started...at the ocean. (source)

Grade level: 5-8
Theme: water cycle
Activity: http://www.tos.org/hands-on/teaching_phys_concepts.pdf

Activity 4.7: Thermal Expansion (p. 39-40). A good grasp of the underlying principles of thermal physics is essential for understanding how the ocean functions and how it impacts climate. Thermal physics is one of the science subjects that students are familiar with and experience on a daily basis, but intertwined with the experiential knowledge they bring to class comes a mixed bag of misconceptions that must be identified and addressed. Example misconceptions include an inability to differentiate between heat and temperature, the notion that transfer of heat will always result in a temperature rise, and a misunderstanding of the concept of latent heat. The purpose of this activity is to review basic concepts of thermal physics and highlight applications to ocean processes by focusing on the concept of thermal expansion.

Most substances expand when heated and contract when cooled. As the temperature of most substances increases, their molecules vibrate faster and move farther apart, occupying a larger space. When these substances are cooled, their molecules vibrate slower and remain closer to each other. Note that freshwater below 4°C actually expands when cooled, a phenomena known as the anomaly of water. Thermal expansion is the principle by which a liquid thermometer works. In the ocean, thermal expansion is thought to contribute significantly to sea level rise on decadal-to-century-long time scales. However, thermal effects appear to be influenced by decadal climaterelated fluctuations, making it difficult to estimate the long-term contribution of thermal expansion to sea level rise. Current estimates suggest that thermal expansion is responsible for 25 percent to 50 percent of observed sea level rise.

In this activity, we look at thermal expansion and attempt to predict what will happen to the ocean's volume if ocean waters become warmer.

Grade levels: K-4, 9-12
Themes: ocean circulation, water cycle
Video: water_everywhere_02.flv

Paula Bontempi: "The water evaporates and goes into the atmosphere, and then it doesn't necessarily just turn around and fall as rain or snow."

Condensation is the process by which water vapor molecules cool, stick together, and become liquid again in cloud formation. This often happens high in the atmosphere where the temperature is much lower than it is near the surface.

Paula Bontempi: "What happens in the atmosphere is, just like we have currents in the ocean, we have winds in the atmosphere that actually, to some extent, drive what goes on in the ocean currents. Materials in the atmosphere can travel a great distance, sometimes a quarter of a way around the world, just until they get to the point where they actually turn into rain or snow and thereby fall back to the ocean or fall back to the land. This is called precipitation. If the water molecule falls on the land as snow, it may be stored for a very long period of time in a polar ice sheet or mountain glacier, depending on climate conditions."

Matt Rodell: "When rain falls or the snow melts, typically the next place it goes, it infiltrates the soil. So soil is not solid. It's not like a rock, there are pore spaces that can be filled with water and typically there is a certain amount of water in the soil at all times. If soil was completely dry, plants wouldn't be able to grow." (source)

Grade levels: K-4, 9-12
Themes: ocean circulation, water cycle
Video: WC_precipitation_IPOD.m4v.flv

This animation displays the intensity of precipitation as it flows around the globe, showing heavy precipitation in orange/yellow and light precipitation in purple. This video is a clip taken from Water, Water Everywhere which incorporates audio not included in this clip.

Water regulates climate, storing heat during the day and releasing it at night. Water in the ocean and atmosphere carry heat from the tropics to the poles. The process by which water moves around the earth, from the ocean, to the atmosphere, to the land and back to the ocean is called the water cycle.

This animation was created using data from the GEOS-5 atmospheric model on the cubed-sphere, run at 14-km global resolution for 30-days. Variables animated here include evaporation, water vapor and precipitation. This animation is time synchronous throughout the animation to allow cross fades during compositing. (source)

Grade level: 9-12
Theme: water cycle
Video: water_everywhere_03.flv

If soil becomes saturated, any additional rainfall will collect in puddles and streams. Soil water that percolates deep enough will help to recharge an aquifer.

Matt Rodell: "An aquifer is any underground geologic formation that stores water so it's typically either rock with a lot of cracks in it, or it's (a) sandy layer. Sand has a lot of pore space in it and can store a lot of water."

A water molecule might remain in an aquifer for more than a million years. More likely, it would help to replenish a stream, which would feed into lakes and rivers. Eventually, the water molecule will return to where it started: the ocean.

People also have a role in the water cycle. By pumping water out of the ground for irrigation, cutting down forests for development and building roads and other concrete surfaces that lead to runoff, people can have a serious impact on the path a water molecule takes.

Matt Rodell: "The most obvious way that people affect the water cycle are the ways that we control the water after it's fallen on the land surface as rain or melts as snow... But we have put in dams and rivers to hold this water. We've also pumped the groundwater out and used that. So it's these water resources, as we call them, are really us taking a natural part of the water cycle and using it to our benefit."

Grade levels: K-4, 5-8, 9-12
Themes: ocean circulation, water cycle
Video: water_everywhere_01.flv

Water is all around us, and its importance to nearly every process on earth cannot be underestimated. It is the only compound that can be found naturally as a liquid, gas, and solid. The process by which water moves around the Earth, from the ocean to the atmosphere to the land, and back to the ocean, is called the water cycle. Water regulates climate, storing heat during the day and releasing it at night, and carries heat from the tropics to the poles, by sea and by air.

Let's follow a single molecule of water, beginning in the ocean, through the paths it might take before eventually winding up right where it started - back in the big blue sea. The fuel for this journey will be provided by our planet's prime energy source: the sun. During the day, the sun heats up the air and ocean surface, causing water molecules to evaporate. Evaporation occurs when a liquid molecule of water escapes into the air as a gas.

This scientific visualization shows how water evaporation, indicated in turquoise, is driven by the energy of the sun. Notice how the rate of evaporation pulses over land: it speeds up during the day and almost disappears at night. Over the ocean, evaporation appears to remain constant, both day and night. Water in the air in gas form is known as water vapor. The molecule is now fresh water, having left the ocean salt and other particles behind. (source)

Grade levels: K-4, 5-8, 9-12
Themes: ocean circulation, water cycle
Video: Evap_and_clock_IPOD.m4v.flv

This animation of evaporation shows how heating from the sun causes increased evaporation over land during the day. This video is a clip taken from Water, Water Everywhere which incorporates audio not included in this clip.

Water regulates climate, storing heat during the day and releasing it at night. Water in the ocean and atmosphere carry heat from the tropics to the poles. The process by which water moves around the earth, from the ocean, to the atmosphere, to the land and back to the ocean is called the water cycle.

This animation was created using data from the GEOS-5 atmospheric model on the cubed-sphere, run at 14-km global resolution for 30-days. Variables animated here include evaporation, water vapor and precipitation. This animation is time synchronous throughout the animation to allow cross fades during compositing. (source)

Grade levels: K-4, 5-8, 9-12
Themes: ocean circulation, water cycle
Video: WC_evaporation_IPOD.m4v.flv

This animation of evaporation shows how heating from the sun causes increased evaporation over land during the day. This video is a clip taken from Water, Water Everywhere which incorporates audio not included in this clip.

Water regulates climate, storing heat during the day and releasing it at night. Water in the ocean and atmosphere carry heat from the tropics to the poles. The process by which water moves around the earth, from the ocean, to the atmosphere, to the land and back to the ocean is called the water cycle.

This animation was created using data from the GEOS-5 atmospheric model on the cubed-sphere, run at 14-km global resolution for 30-days. Variables animated here include evaporation, water vapor and precipitation. This animation is time synchronous throughout the animation to allow cross fades during compositing. (source)

Grade levels: K-4, 5-8, 9-12
Themes: ocean circulation, water cycle
Video: WC_vapor_IPOD.m4v.flv

This animation portrays the flow of atmospheric water vapor around the world. This video is a clip taken from Water, Water Everywhere which incorporates audio not included in this clip.

Water regulates climate, storing heat during the day and releasing it at night. Water in the ocean and atmosphere carry heat from the tropics to the poles. The process by which water moves around the earth, from the ocean, to the atmosphere, to the land and back to the ocean is called the water cycle.

This animation was created using data from the GEOS-5 atmospheric model on the cubed-sphere, run at 14-km global resolution for 30-days. Variables animated here include evaporation, water vapor and precipitation. This animation is time synchronous throughout the animation to allow cross fades during compositing. (source)

Grade levels: K-4, 5-8, 9-12
Themes: ocean circulation, water cycle
Video: WC_SST_IPOD.m4v.flv

This animation of sea surface temperature shows the transport of heat along the ocean's surface. This video is a clip taken from Water, Water Everywhere which incorporates audio not included in this clip.

Water regulates climate, storing heat during the day and releasing it at night. Water in the ocean and atmosphere carry heat from the tropics to the poles. The process by which water moves around the earth, from the ocean, to the atmosphere, to the land and back to the ocean is called the water cycle.

Data for this animation was derived from a model run of ECCO's Ocean General Circulation Model of heat along the ocean's surface. (source)

Grade levels: K-4, 5-8, 9-12
Themes: ocean circulation, water cycle
Video: WC_rivers_IPOD.m4v.flv

In this animation, pulsing of the global rivers highlights the flow of water from the continents back into the oceans. This video is a clip taken from Water, Water Everywhere which incorporates audio not included in this clip.

Water regulates climate, storing heat during the day and releasing it at night. Water in the ocean and atmosphere carry heat from the tropics to the poles. The process by which water moves around the earth, from the ocean, to the atmosphere, to the land and back to the ocean is called the water cycle. (source)

Grade level: 9-12
Theme: water cycle
Video: water_everywhere_04.flv

The water cycle affects and is affected by climate variations.

Matt Rodell: "The water cycle is one of the ways that we will really feel any changes in climate. So climate changes will feed back to water cycle changes, things like how much precipitation an area receives, the frequency of droughts and floods and this sort of thing."

The water cycle is the adventurous journey that water takes through the oceans, atmosphere, and land, driven by the sun. Improving our understanding of the water cycle and how it is changing will be critical for future decisions related to water management, agriculture, natural resources, and climate change.