Solar Energy and WindsSolar Energy: Sun is distributing energy to the Earth in a form of ultraviolet rays. But of course, every single rays are not hitting the surface of the Earth. 30% of the incoming solar energy from the Sun is reflected back into space by clouds, dust in the air, gases, and by Earth's surface. 20% is absorbed by clouds and gases. 50% passes through the atmosphere and is absorbed by the surface. The major form of radiant energy that enters Earth is visible light and the infrared is reradiated from the Earth to the atmosphere. The greenhouse effect warm the lower atmosphere. The energy from the Sun is absorbed by certain gases (water vapor, carbon dioxide) and it release energy back to Earth's surface, which warms the surface. Also, the solar energy is transferred within the troposphere in three ways. They are radiation, convection, and conduction. These three ways will be discussed below.
Wind: As we discussed in the previous section, there is a direct and indirect distribution of energy from the Sun. This create a difference in air pressure between the pole and the equator. The Earth tries to stabilize this difference by creating wind. Wind is a natural flow of air from high pressure to low pressure. When hot air rise in the tropic, cooler air from the pole replace that region. Wind will be important when we talk about erosion of the Earth and this will be discussed later in the website. There are many types of wind and it will be discussed below. |
Radiation, Convection, Conduction |
Solar energy from the Sun heats the land in a process called radiation. Conduction transfers heat from land and water directly to the few maters of air nearest Earth's surface. Convection moves heat through the troposphere. In this process, hot air rises (less dense) and cold air sinks (highly dense) and this circulation continues. Convection is happening throughout the entire Earth and this process is related to almost all of the concepts.
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Types of Wind
Local Wind• Wind that blows over a short distance
• Caused by the unequal heating of Earth's surface within a small region |
Sea/Land BreezeSea: the cooler air over the water flows toward the land
Land:cooler air over land moves toward water |
Global Winds• Winds that blow over long distances from a specific direction
• Also caused by unequal heating of Earth • Trade winds, westerlies, and polar easterlies are examples of global winds |
Convection Cells• Series of huge bands of global winds
• Caused by temperature variations across Earth's surface |
Monsoon• Wind system that is characterized by seasonal reversal of direction
• Similar to land and sea breezes except that they occur on a much wider scale and longer time frame |
Jet Stream• A belt of high-speed wind in the upper troposphere
• Caused by great differences in air pressure that develop at high altitudes |
Coriolis Effect |
Coriolis effect is a phenomenon that causes fluids, like water and air, to curve as they travel across or above Earth’s surface. The Earth is a sphere that is rotating from West to East. Since it is a sphere, equator is moving faster than the pole. So, the Coriolis effect is tugging the volume of air to the right, which creates counter clockwise spin at the Northern hemisphere. On the other hand, the volume of air is tugged to the left, which creates clockwise spin in the Southern hemisphere.
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