![]() We divide by 4 since the solar energy is spread over the surface of the planetary sphere. This is energy delivered at the top of the atmosphere. ‘a' is planetary albedo (0.31, this is the proportion of incoming radiation reflected to space and lost) Ω is the solar constant (solar radiation reaching Earth, in Watts m -2, about 1367). In general terms (Harte 1988), the energy absorbed by the Earth can be written as: The wavelengths are dictated by the temperature of the emitter (Earth is cooler than the sun so it radiates at a longer wavelength). The energy coming from the sun is principally in the shorter (including visible) wavelengths (0.3–1µm yellow-green visible) while the energy emitted by Earth surfaces is in the longer wavelength infrared (4–11µm). Ultimately, the temperature of the planet will be that at which energy absorbed balances energy lost. This energy warms the planet, but the warming also causes Earth to start radiating energy back into space. The climate system is powered by radiation from the sun, of which approximately 49% is absorbed by the Earth's surface, and 20% is absorbed by the atmosphere (Kiehl & Trenberth 1997). But, if we crunch the numbers (even in a simple way) we will find that keeping the planet warm depends a good deal on the Earth amplifying the solar heat supply. If you are pale skinned (like me) and have roasted at the beach, it is hard to believe that the fierce glare of the mid-summer sun actually doesn't even provide enough energy to keep the Earth above freezing. It also provides links to more detailed articles on regional climate dynamics both in the modern and in the past. This article examines these three basics, explaining the concepts involved using simple examples of principles. These systems respond to the planetary energy balance and also interact with one another via teleconnections. These are: (a) solar heating of the planet balanced by energy loss to space (b) atmosphere, ocean, land, and ice responses to heating which provide feedbacks that either mitigate or accentuate planetary temperature changes and (c) regional environmental systems which have innate patterns of climate variability dictated by their unique physical-chemical-biological conditions. There are three basics that dictate Earth's climate, and our environment. For example, the glaciation of Earth (195,000–123,000 years ago) reduced humanity to a tiny population clinging to a coastline of South Africa (Marean 2010). It is climate which sets our long term living conditions, and climate has impacted humans since we appeared on the planet. Weather is what might inconvenience you for a few days, but at a deeper level, climate dictates what that weather might be. There is no more common chat topic than the weather. ![]()
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