ART9.1 Question 1. How much of the Earth s mass is in the hydrosphere? Name: Period: Answer 2. How much of the Earth s surface is covered in oceans? 3. How much of the Earth s water is found in oceans, and in ice? 4. What other bodies in the solar system have hydrospheres? 5. How does the size of Europa s hydrosphere compare to Earth s? 6. How long do different parts of the cryosphere last? 7. Where is most of the world s ice? 8. What happens to ocean levels as ice melts? 9. Where does the salt in the ocean s come from? 10. How is salinity expressed? 11. What is the average, and range of salinity in the ocean s? 12. What is the salinity of freshwater? 13. What are ocean currents? 14. What are some of the more prominent currents? 15. What causes surface currents? 16. Which direction do gyre s turn? 17. What creates mounds in the ocean s surface?
ART9.1 18. Where are deep water currents found? Name: Period: 19. What causes differences in density of ocean water? 20. Why is thermohaline circulation is known as the Global Conveyor Belt? 21. Why are ocean currents important to the world s weather? 22. Why are places like Europe warmer than other areas at similar latitudes? 23. What moves icebergs into shipping lanes in the North Atlantic shipping lanes? 24. How could ocean currents be used to generate energy? Using the articles, define the following terms: 1. salinity 2. cryosphere 3. hydrosphere 4. brackish water 5. osmosis 6. surface currents 7. gyre 8. thermohaline circulation
Hydrosphere by Jerry Coffey liquid. Some people fear that global warming will cause the melting and collapse of large ice sheets resulting in sea level rise. Rising sea levels could devastate coastal cities, displace millions of people, and wreak havoc on freshwater systems and habitats. Liquid water makes up a large potion of the hydrosphere. A hydrosphere in physical geography describes the combined mass of water found on, under, and over the surface of a planet. The total mass of the Earth s hydrosphere is about 1.4 10 24 grams, which is about 0.023% of the Earth s total mass. Around 2 10 19 grams of this is the Earth s atmosphere. In addition, 71% of the Earth s surface, an area of 361 million square kilometers, is covered by ocean. Having liquid water makes the Earth a special place. Our planet has a very nice temperature range that allows water to remain in its liquid state. If we were a colder object like Pluto, it would not matter how much water there was on the planet; it would all be frozen. On the other hand, if we were on a very hot planet, all of the water would be in a gaseous state. Water vapor and solid water are useless to the living organisms found on Earth. The world s oceans contain 97% of the water in the hydrosphere, most of which is salt water. Ice caps, like that found covering Antarctica, and glaciers that occupy high alpine locations, compose a little less than 2% of all water found on earth. Although that is a small amount, the water stored as ice in glaciers would have a great impact on the environment if it were to melt into a The Earth is not the only solar body that is thought to have a hydrosphere. A thick hydrosphere is thought to exist around the Jovian moon Europa. The outer layer of this hydrosphere is almost entirely frozen, but current models predict that there is an ocean up to 100 km in depth underneath the ice. This ocean remains in a liquid form due to the tidal flexing of the moon in its orbit around Jupiter. The volume of Europa s hydrosphere is 3 10 18 meters cubed, which is about 2.3 times that of the Earths hydrosphere. It has been theorized that the Jovian moon Ganymede and the Saturn moon Enceladus may also possess subsurface oceans. The hydrosphere is a delicate aspect of the Earth. Many things have to remain in balance in order for it to remain in stasis. There needs to be more study to extrapolate a definite cause and effect between the hydrosphere and global warming. Cryosphere by Jerry Coffey The cryosphere is the portions of the Earth s surface where water is in solid form, including sea ice, lake ice, river ice, snow cover, glaciers, ice caps, ice sheets, and frozen ground like permafrost. Due to its very nature the cyrosphere is always changing in its area and volume and overlaps quite a bit with the hydrosphere. This is an integral part of the global climate system. It has important linkages and feedbacks generated through its influence on surface energy and moisture fluxes, cloud formation, precipitation, and atmospheric 9 - ART9.1 Page 1 of 5
and oceanic circulation. This means that it plays an important role in the global climate. The two previous articles reprinted with permission of : Universe Today. www.universetoday.com Ocean Water: Salinity Office of Naval Research The residence time of water in each subsystem(snow, ice, permafrost) varies widely. Snow cover and freshwater ice are essentially seasonal. Most sea ice, except for ice in the central Arctic, lasts only a few years if it is not seasonal. A water particle in a glacier, ice sheet, or ground ice(permafrost) may remain frozen for 10-100,000 years or longer, and deep ice in parts of East Antarctica may have an age approaching 1 million years. Most of the world s ice volume is in Antarctica, but by area Northern Hemisphere winter snow and ice is the largest, amounting to an average 23% of hemispheric surface area in January. The large area and the important climatic roles of snow and ice, indicate that the ability to observe and model snow and icecover extent, thickness, and radiative and thermal properties is of particular significance for climate research. The cryosphere is the part of the atmosphere that shows some of the most easily observable effects of global warming. As the oceans warm, the ice recedes. The melting ice can raise the levels of the oceans around the world. It is actually a cycle. As the ice melts it allows the planet to stay warmer and more ice melts. NASA satellites have documented a rapid decrease in ice sheets that coincides with a rapid rise in global sea levels. Did you ever wonder why the oceans are filled with salt water instead of fresh? Just where did the salt come from? And is it the same salt you find on a dining room table? Most of the salt in the oceans came from land. Over millions of years, rain, rivers, and streams have washed over rocks containing the compound sodium chloride (NaCl), and carried it into the sea. You may know sodium chloride by its common name: table salt! Some of the salt in the oceans comes from undersea volcanoes and hydrothermal vents. When water evaporates from the surface of the ocean, the salt is left behind. After millions of years, the oceans have developed a noticeably salty taste. Different bodies of water have different amounts of salt mixed in, or different salinities. Salinity is expressed by the amount of salt found in 1,000 grams of water. Therefore, if we have 1 gram of salt and 1,000 grams of water, the salinity is 1 part per thousand, or 1 ppt. The average ocean salinity is 35 ppt. This number varies between about 32 and 37 ppt. Rainfall, evaporation, river runoff, and ice formation cause the variations. For example, the Black Sea is so diluted by river runoff, its average salinity is only 16 ppt. Freshwater salinity is usually less than 0.5 ppt. Water between 0.5 ppt and 17 ppt is called brackish. Estuaries (where fresh river water meets salty ocean water) are examples of brackish waters. Most marine creatures keep the salinity inside their bodies at about the same concentration as the water outside their bodies because water likes a balance. If an 9 - ART9.1 Page 2 of 5
animal that usually lives in salt water were placed in fresh water, the fresh water would flow into the animal through its skin. If a fresh water animal found itself in the salty ocean, the water inside of it would rush out. The process by which water flows through a semi-permeable membrane (a material that lets only some things pass through it) such as the animal's skin from an area of high concentration (lots of water, little salt) to an area of low concentration (little water, lots of salt) is called osmosis. This is also why humans (and nearly all mammals) cannot drink salt water. When you take in those extra salts, your body will need to expel them as quickly as possible. Your kidneys will try to flush the salts out of your body in urine, and in the process pump out more water than you are taking in. Soon you'll be dehydrated and your cells and organs will not be able to function properly. Ocean Currents From Amanda Briney Ocean currents are the vertical or horizontal movement of both surface and deep water throughout the world s oceans. Currents normally move in a specific direction and aid significantly in the circulation of the Earth s moisture, the resultant weather, and water pollution. Oceanic currents are found all over the globe and vary in size, importance, and strength. Some of the more prominent currents include the California and Humboldt Currents in the Pacific, the Gulf Stream and Labrador Current in the Atlantic, and the Indian Monsoon Current in the Indian Ocean. These are just a sampling of the seventeen major surface currents found in the world s oceans. In addition to their varying size and strength, ocean currents differ in type. They can be either surface or deep water. Surface currents are those found in the upper 400 meters (1,300 feet) of the ocean and make up about 10% of all the water in the ocean. Surface currents are mostly caused by the wind because it creates friction as it moves over the water. This friction then forces the water to move in a spiral pattern, creating gyres. In the northern hemisphere, gyres move clockwise and in the southern they spin counterclockwise. The speed of surface currents is greatest closer to the ocean s surface and decreases at about 100 meters (328 ft) below the surface. 9 - ART9.1 Page 3 of 5
Because surface currents travel over long distances, the Coriolis force also plays a role in their movement and deflects them, further aiding in the creation of their circular pattern. Finally, gravity plays a role in the movement of surface currents because the top of the ocean is uneven. Mounds in the water form in areas where the water meets land, where water is warmer, or where two currents converge. Gravity then pushes this water down slope on the mounds and creates currents. Deep water currents, also called thermohaline circulation, are found below 400 meters and make up about 90% of the ocean. Like surface currents, gravity plays a role in the creation of deep water currents but these are mainly caused by density differences in the water. Density differences are a function of temperature and salinity. Warm water holds less salt than cold water so it is less dense and rises toward the surface while cold, salt laden water sinks. As the warm water rises though, the cold water is forced to rise through upwelling and fill the void left by the warm. By contrast, when cold water rises, it too leaves a void and the rising warm water is then forced, through downwelling, to descend and fill this empty space, creating thermohaline circulation. Thermohaline circulation is known as the Global Conveyor Belt because its circulation of warm and cold water acts as a submarine river and moves water throughout the ocean. Finally, seafloor topography and the shape of the ocean s basins impact both surface and deep water currents as they restrict areas where water can move and "funnel" it into another. Because ocean currents circulate water worldwide, they have a significant impact on the movement of energy and moisture between the oceans and the atmosphere. As a result, they are important to the world s weather. The Gulf Stream for example is a warm current that originates in the Gulf of Mexico and moves north toward Europe. Since it is full of warm water, the sea surface temperatures are warm, which keeps places like Europe warmer than other areas 9 - ART9.1 Page 4 of 5
at similar latitudes. The Humboldt Current is another example of a current that affects weather. When this cold current is normally present off the coast of Chile and Peru, it creates extremely productive waters and keeps the coast cool and northern Chile arid. However, when it becomes disrupted, Chile s climate is altered and it is believed that El Niño plays a role in its disturbance. Like the movement of energy and moisture, debris can also get trapped and moved around the world via currents. This can be man-made which is significant to the formation of trash islands or natural such as icebergs. The Labrador Current, which flows south out of the Arctic Ocean along the coasts of Newfoundland and Nova Scotia, is famous for moving icebergs into shipping lanes in the North Atlantic. Currents play an important role in navigation as well. In addition to being able to avoid trash and icebergs, knowledge of currents is essential to the reduction of shipping costs and fuel consumption. Today, shipping companies and even sailing races often use currents to reduce time spent at sea. Finally, ocean currents are important to the distribution of the world s sea life. Many species rely on currents to move them from one location to another whether it is for breeding or just simple movement over large areas. Today, ocean currents are also gaining significance as a possible form of alternative energy. Because water is dense, it carries an enormous amount of energy that could possibly be captured and converted into a usable form through the use of water turbines. Currently this is an experimental technology being tested by the United States, Japan, China, and some European Union countries. Whether ocean currents are used as alternative energy, to reduce shipping costs, or in their natural to state to move species and weather worldwide, they are significant to geographers, meteorologists, and other scientists because they have a tremendous impact on the globe and earth-atmosphere relations. 9 - ART9.1 Page 5 of 5