Because the low latitudes of the Earth, the areas near the equator, receive more heat

　　Than the latitudes near the poles, and because the nature of heat is to expand and move,

　　Heat is transported from the tropics to the middle and high latitudes. Some of this heat is

　　Line Moved by winds and some by ocean currents, and some gets stored in the atmosphere in

　　(5) the form of latent heat. The term “latent heat” refers to the energy that has to be used to

　　Convert liquid water to water vapor. We know that if we warm a pan of water on a stove,

　　it will evaporate, or turn into vapor, faster than if it is allowed to sit at room temperature.

　　We also know that if we hang wet clothes outside in the summertime they will dry faster

　　than in winter, when temperatures are colder. The energy used in both cases to change

　　(10) liquid water to water vapor is supplied by heat—supplied by the stove in the first case

　　and by the Sun in the latter case. This energy is not lost. It is stored in water vapor in the

　　atmosphere as latent heat. Eventually, the water stored as vapor in the atmosphere will

　　condense to liquid again, and the energy will be released to the atmosphere.

　　In the atmosphere, a large portion of the Sun’s incoming energy is used to evaporate

　　(15) Water, primarily in the tropical oceans. Scientists have tried to quantify this proportion

　　of the Sun’s energy. By analyzing temperature, water vapor, and wind data around the

　　globe, they have estimated the quantity to be about 90 watts per square meter, or nearly

　　30 percent of the Sun’s energy. Once this latent heat is stored within the atmosphere, it

　　can be transported, primarily to higher latitudes, by prevailing, large-scale winds. Or it

　　(20) can be transported vertically to higher levels in the atmosphere, where it forms clouds

　　and subsequent storms, which then release the energy back to the atmosphere.

　　31. The passage mainly discusses how heat

　　is transformed and transported in the Earth’s atmosphere

　　is transported by ocean currents

　　can be measured and analyzed by scientists

　　moves about the Earth’s equator

　　32. The passage mentions that the tropics differ from the Earth’s polar regions in which of the following ways?

　　The height of cloud formation in the atmosphere

　　The amount of heat they receive from the Sun

　　The strength of their largescale winds.

　　The strength of their oceanic currents

　　33. The word “convert” line 6 is closest in meaning to

　　mix

　　change

　　adapt

　　reduce

　　34. Why does the author mention “the stove” in line 10?

　　To describe the heat of the Sun

　　To illustrate how water vapor is stored

　　To show how energy is stored

　　To give an example of a heat source