Insolation, Differential Heating and Storm Generation

How and why are storms produced?

Storms of all kinds are produced as the result of differential heating of the Earth's surface. As incoming solar radiation (insolation) makes its way through the Earth's atmosphere en route to the surface, some of the energy is reflected back to space by the atmosphere while some is absorbed and converted to heat energy. The resulting energy distribution across the earth varies as a function of latitude. Excess heat energy absorbed by the land, water, and air at the equator is transported poleward to areas with net heat deficits. This heat is transported both in the atmosphere and in the ocean as ocean currents travel poleward. Storms are generated in the process, especially when warm, energy-rich air masses collide with cooler air-masses. NASA's Earth Observatory has a great website that explores exactly how the Earth's heat engine works to absorb and redistribute the sun's energy (Figure 5.12). Take a few moments; read the first few pages of the observatory website.

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Figure 5.12: Image clip from NASA's Earth Observatory website. The website explains how the Earth's climate system works to redistribute heat energy that is in surplus in the low to mid latitudes into higher latitude settings where heat energy is in deficit. The interaction and movement of masses of warm and cold air masses and high and low pressure systems lead to the multiplicity of storms that impact the shorelines of all water bodies on Earth.
Credit: NASA: EO: Climate and Earth's Energy Budget

Learning Check Point

To show your understanding of how incoming solar radiation varies by latitude and by season, you should be able to make succinct statements about how the total energy received each day at the top of the Earth's atmosphere is different between the poles and the equator. For instance, you should be able to answer the following questions:

Question 1 - Essay

How much energy (in megajoules per square meter per day) is delivered to earth at the equator in January? Likewise how much energy is delivered to 45 degrees N? and to the Arctic Circle?

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Question 2 - Essay

How much energy (in megajoules per square meter per day) is delivered to the equator in June? Likewise how much energy is delivered to 45 degrees S? and to the Antarctic Circle?

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Question 3 - Essay

Based on your answers, why is the amount of energy delivered to the Antarctic and Artic Circles less than 5 megajoules per square meter per day in Jun and July versus December and January respectively?

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