Explain how the sun heats the Earth and the impact on convection within the atmosphere and hydrosphere
Answers
When the Sun’s energy moves through space, it reaches Earth’s atmosphere and finally the surface. This radiant solar energy warms the atmosphere and becomes heat energy. This heat energy is transferred throughout the planet’s systems in three ways: by radiation, conduction, and convection.
Conduction “is the transfer of heat from one molecule to another within a substance” (Rousay, 2006, par. 5). Conduction transfers heat between substances that are in direct contact with each other. Heat energy moves from warmer to colder areas. Take the example of a metal soup spoon that transfers the heat of the soup to your fingers holding that spoon. Metal is an excellent conductor of heat. The tightly packed molecules in the solid metal spoon vibrate in their positions, quickly transferring energy from molecule to molecule until this energy reaches your fingers. The hotter the molecules are, the faster they vibrate and bump against each other, moving heat through the solid metal spoon. In terms of heating Earth’s surface, though, it “turns out that air is an extremely poor conductor of heat. Therefore, conduction is only important in the atmosphere within the first several millimeters closest to the surface. How then does the air transfer energy from one region to another?” (Rousay, par. 5)
Here is where convection comes in. “Convection is the transfer of heat through the movement of a fluid such as water or air. This type of heat transfer can occur in liquids and gases because they move freely, making it possible to set up warm or cold currents” (Rousay, par. 6). This transfer of heat energy by the actual movement of the heated molecules is called convection, a method of energy transfer that can take place in fluids like air and water. “As the Earth’s surface absorbs sunlight, certain portions of the surface absorb more than other portions. The Earth’s surface and the air near the surface heats unevenly. The warmest air expands, [becoming] less dense than the surrounding cool air, [which] becomes buoyant and rises. These rising “bubbles” of warm air, called thermals, act to transfer heat up into the atmosphere” (Rousay, par. 6). These thermals can result in the formation of clouds, which in turn can serve as another vector of energy transfer.