Solar Radiation
Almost all of the energy available to the Earth's surface and atmosphere comes from the sun in the form of solar radiation (light from the sun, including invisible ultraviolet and infrared light). Variations in the amount of solar radiation reaching different parts of the Earth are a principal driver of global and regional climate. Averaged over a year, latitude is the most important factor determining the amount of solar radiation reaching the top of the atmosphere; the incident solar radiation decreases smoothly from the Equator to the poles. This variation leads to the most obvious observation of regional climate: temperature tends to decrease with increasing latitude.
In addition the length of each day, which is determined by the season, has a significant impact on the climate. The 24-hour days found near the poles in summer result in a large daily-average solar flux reaching the top of the atmosphere in these regions. On the June solstice 36% more solar radiation reaches the top of the atmosphere over the course of the day at the North Pole than at the Equator (Serreze and Barry, 2005). However in the six months from the September equinox to March equinox the North Pole receives no sunlight. Images from the NOAA's North Pole Web Cam illustrate Arctic daylight, darkness and the changing of the seasons.
The climate of the Arctic also depends on the amount of sunlight reaching the surface, and the amount that the surface absorbs are also important. Variations in the frequency of cloud cover can cause significant variations in the amount of solar radiation reaching the surface at locations with the same latitude. Changes in surface conditions, such as the appearance or disappearance of snow or sea ice, can cause large changes in the surface albedo, the fraction of the solar radiation reaching the surface that is reflected rather than absorbed.
Read more about this topic: Climate Of The Arctic
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