The meteorologist Wladimir Peter Koppen created a classification system for climate regions in 1920 that helped people better understand what factors went into the weather. Koppen evaluated average temperatures and the rate of precipitation in different regions. After this evaluation, he determined that there were five regions: tropical, dry/desert, hot moderate, cold moderate and polar. He further described these five main regions by the amount and nature of precipitation they receive and the temperature patterns in the region.
As the Earth tilts on its axis and revolves around the sun, radiation is distributed differently in different areas depending on the regions' proximity to the sun. Therefore, the latitude of the region is a key factor in the climate in that region. Another is air mass. Air mass is a large amount of air with similar properties. When two large air masses meet, they often collide rather than joining to form one larger, homogeneous air mass, according to meteorologist Jeff Haby. The combinations and movement of air masses determine, in part, precipitation, humidity, and varying air and surface temperatures from region to region.
The circulation of air creates high- and low-pressure zones, which strongly influence climate regions. For example, high-pressure zones are usually associated with cooler, dryer air because the air is more dense, so the air is circulated outward, causing cooler air. In a low-pressure zone, air is circulated upward and stays within the atmosphere, often causing clouds and precipitation.
When the wind moves ocean currents, it also moves surface water with it. This movement of water creates pressure in the atmosphere. These pressure zones move heat from the equator to the poles, an example of heat transfer. This shows also how patterns of prevailing winds, as well as land and sea distribution can affect climate regions. Some regions closer to the water, because of the air circulating over the water, will be more mild than landlocked regions.
Mountains and altitude significantly influence climate regions. The higher the altitude, the thinner the air and the less it is able to retain and absorb heat. So climate regions in higher altitudes, for example, at the peaks of mountains, will have cooler climates. Mountains can also act as a barrier to precipitation, causing surrounding land to be dryer. Due to wind patterns, one side of a mountain could be wet while the other side is desert.
