Ecology - Chapter 5 Review Questions

Explain the process that causes El Niño- Southern Oscillation events.

Changes in the strength of trade winds near the equator can have major impacts on the climates of the world. (a) In most years, strong trade winds push warm surface waters away from the west coast of South America. This causes cold, deep waters to upwell along the coast. (b) During an ENSO year, the trade winds weaken or reverse and the warm surface water moves from west to east. As a result, warm water builds up along the west coast of South America and prevents the upwelling of the cold, deep water. This change in ocean circulation alters climates around the world.

Based on your knowledge of the ocean conveyor belt, how might melting of the ice in the Arctic Ocean affect the climate of Europe?

Less Salt Water - Destroys thermohaline circulation.

Explain the steps involved in the greenhouse effect.

Of the solar radiation that strikes Earth, some is reflected back into space and the rest penetrates the atmosphere where much of it warms clouds and the planet's surface. These warmed objects emit infrared radiation back toward the atmosphere where it is absorbed by greenhouse gases. The warmed greenhouse gases re-emit infrared radiation back toward Earth, which causes the surface to warm further.

Why do many mountain ranges have high precipitation on one side and low precipitation on the other side?

Rain shadows. When winds carry warm moist air up over a mountain, the air cools and releases much of its moisture as precipitation. After crossing the mountain, the now dry air descends down the mountain, which causes the environment on this side of the mountain to be very dry.

How does the human production of greenhouse gases lead to global warming?

The concentrations of greenhouse gases in the atmosphere are increasing. The concentration of CO2 in the atmosphere has substantially increased over the past 2 centuries due to increased combustion of fossil fuels by automobiles, electric generating plants, and other industrial processes. At the same time, there have also been increases in methane and nitrous oxide from a variety of anthropogenic sources that include agriculture, landfills, and the combustion of fossil fuels. Finally, there are gases that are not naturally produced, such as chlorofluorocarbons that have been manufactured to serve as propellants in aerosol cans and as refrigerants in freezers, refrigerators, and air conditioners. Although these human-created compounds exist at much lower concentrations than water vapor or CO2, each molecule can absorb much more infrared radiation than H2O and CO2 , and persists in the atmosphere for hundreds of years.

Why is solar energy input greater near the equator than near the poles?

The intensity of solar radiation that strikes an area also depends on the angle of the Sun's rays. You can see that when the Sun is positioned directly above the equator, the rays of the Sun strike Earth at a right angle. This causes a large quantity of solar energy to strike a small area. In contrast, near the poles the rays of the Sun strike Earth at an oblique angle, which causes the solar energy to spread over a larger area.

Explain the factors that drive the movement of air in Hadley cells.

The upward movement of air is the driving force behind atmospheric convection currents, but it is just the first of a series of steps in the process. Once the cool, dry air is displaced horizontally toward the poles, it begins to sink back toward Earth at approximately 30° N and 30° S latitudes. As Figure 5.6 illustrates, this air sinks toward Earth where increased pressure causes it to compress. As the air compresses, it experiences adiabatic heating and decreased humidity. By the time the air falls back to the surface of Earth, it is hot and dry. This explains why many of the major deserts of the world—which are characterized by hot, dry air—are located at approximately 30° N and 30° S latitudes. Once this hot, dry air reaches the ground, it flows back toward the equator, completing the air circulation cycle. The two circulation cells of air between the equator and 30° N and 30° S latitudes are known as Hadley cells.

Compare and contrast podsolization and laterization.

Under mild temperatures and moderate precipitation, sand grains and clay particles resist weathering and become stable components of the soil. This allows soils to retain relatively high fertility. However, in acidic soils typical of cool, moist regions, clay particles break down in the E horizon, and their soluble ions are transported down to the lower B horizon. This process, known as podsolization, reduces the fertility of the soil's upper layers. subtropical regions, soils weather to great depths. One of the most conspicuous features of weathering under these conditions is the breakdown of clay particles, which causes silicon to leach from the soil and leaves oxides of iron and aluminum to predominate throughout the soil profile—a process that is called laterization. The iron and aluminum oxides give such soils a characteristic reddish coloration. Even though the rapid decomposition of organic material in tropical soils contributes an abundance of hydrogen ions, bases formed by the breakdown of clay particles neutralize them. Consequently, lateritic soils are not usually acidic, even though they may be deeply weathered. Regardless of the parent material, weathering reaches deepest, and laterization proceeds farthest, on low-lying soils, such as those of the Amazon basin, where highly weathered surface layers are not eroded away and the soil profiles are very old.

The position of the solar equator moves throughout the year. What does its changing position suggest about the location of the intertropical convergence zone throughout the year?

You can see the effect of the ITCZ movement in Figure 5.7 by examining the patterns of rainfall across three locations in the Western Hemisphere. The city of Mérida, Mexico, lies about 20° N of the equator. The intertropical convergence reaches Mérida only during June, which is why June is the rainy season for Mérida. In comparison, Rio de Janeiro, Brazil, lies about 20° S latitude. The intertropical convergence reaches Rio de Janeiro in December, which is the middle of the rainy season for that city. Close to the equator, in Bogotá, Colombia, the intertropical convergence zone passes overhead twice each year, during the March and September equinoxes. As a result, Bogotá experiences two rainy seasons.

How do the unequal heating of Earth, the Coriolis effect, and atmospheric convection currents work together to drive the movement of ocean gyres?

You can see the effect of the ITCZ movement in Figure 5.7 by examining the patterns of rainfall across three locations in the Western Hemisphere. The city of Mérida, Mexico, lies about 20° N of the equator. The intertropical convergence reaches Mérida only during June, which is why June is the rainy season for Mérida. In comparison, Rio de Janeiro, Brazil, lies about 20° S latitude. The intertropical convergence reaches Rio de Janeiro in December, which is the middle of the rainy season for that city. Close to the equator, in Bogotá, Colombia, the intertropical convergence zone passes overhead twice each year, during the March and September equinoxes. As a result, Bogotá experiences two rainy seasons. Around the globe, ocean circulation patterns are also affected by the dominant wind directions and Coriolis effects. North of the equator, for example, the northeast trade winds push surface water from the northeast to the southwest. At the same time, the Coriolis forces deflect ocean currents to the right. The combination of the two forces causes tropical water above the equator to move from east to west. The topography of ocean basins, particularly the locations of continents, causes these currents to change their direction. At mid-latitudes, the westerlies push surface waters to the northeast. As this occurs, Coriolis forces deflect the ocean currents to the right, which causes the ocean currents to move from west to east at mid- latitudes in the Northern Hemisphere. These large- scale water circulation patterns between continents are called gyres. The direction of the deflections caused by Coriolis forces depends on latitude; gyres move in a clockwise direction in the Northern Hemisphere and in a counterclockwise direction in the Southern Hemisphere.