What Effect Does Geography Have on Climate?
By Amy Harris
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Geography exerts a substantial effect on the climate of a particular locale. This fact has been recognized, to some degree, since the time of the ancient Greeks, when the philosopher and mathematician Pythagoras suggested a connection. This connection was later expanded upon by Aristotle and further developed during and since the 20th century. Four major geographical factors play a significant role in determining climate.
Latitude Factor
Latitude, or distance from the equator, is perhaps the most apparent geographic indicator of climate. In general, the hottest climates are closest to the equator, with climates tending to become increasingly cooler with increasing distance from the equator. There are considerable exceptions to this rule based on other variables, but only to an extent -- for instance, balmy conditions don't occur in Antarctica. Roughly speaking, the Earth can be divided into three overarching categories in terms of temperature and seasons. The tropics, where warmth is the norm, lie between approximately 23.5 degrees south and 23.5 degrees north. Temperate zones, which experience clearly delineated seasons, albeit to varying extents, lie between about 23.5 degrees and 66.5 degrees latitude in each hemisphere. Beyond 66.5 degrees latitude in both hemispheres are the polar regions, where winterlike conditions dominate for most if not all of the year. Latitude also influences the prevailing wind direction. In the tropical and polar regions, winds tend to blow from the east, while in the temperate middle latitudes, winds tend to blow from the west.
Elevation Effects
Elevation, or distance from sea level, also plays a key role in determining a location's climate. In the portion of the atmosphere known as the troposphere -- which contains all of the Earth's landmass, even the tallest of mountains -- temperature decreases with increasing height. This is why snow-capped peaks can be observed in otherwise warm regions. On average, the temperature tends to decrease by approximately 0.65 degrees Celsius for every 100-meter increase in elevation (or 3.8 degrees Fahrenheit per 1,000 feet). As with latitude, however, this is not a firm rule; it is susceptible to influence by outside factors. Also, wind speed varies considerably at differing elevations: The higher the elevation, the stronger the winds tend to blow. This is evidenced by the presence of short, stubby trees -- or the entire lack of trees -- at high elevations, as the high winds, often combined with harshly cold temperatures, inhibit their growth.
Topographical Influences
Topography -- such as mountains, valleys, canyons and plains -- impact climate in ways unrelated to elevation. For instance, large mountain ranges can influence precipitation patterns. Mountains force incoming air to rise; as it does, it cools and condenses, forming clouds and eventually rain or snow, which typically falls on the windward side of the mountains. Hence, areas on the windward side of high mountain ranges experience greater precipitation than areas on the leeward side because the mountains essentially drain the moisture from the air. This effect on the leeward side of the mountain ranges is known as a rain shadow and is responsible for the dry and even desertlike climates of some locations, including much of the American West. Other examples of topographical influence on climate include chilly nights in valleys due to downslope winds and the "heat island" effect in cities in which the concrete landscape contributes to elevated nighttime temperatures.
Proximity to oceans, lakes and other bodies of water exerts considerable influences on an area's climate. Water holds its temperature more readily than air -- that is, it takes longer to heat or cool. Thus, water moderates the temperatures of the air around it, so that locations nearest water bodies experience fewer extremes in temperature, typically failing to become as hot or as cold as locations further inland. Areas closest to the oceans, particularly those near warm ocean currents, also tend to have wetter climates than inland locales. Bodies of water can exert additional effects on climates in certain locations, such as increasing the frequency of fog or causing lake-effect snow, as seen in the U.S. Great Lakes region.
University of Wyoming: Geography and Climate
Iowa State University Polaris Project: Latitude and Climate
National Environmental Education Foundation: Ecosystems, Elevation Gradients and Climate Trends
National Oceanic and Atmospheric Administration: Atmosphere-Ocean Climate Interactions
Based in western New York, Amy Harris began writing for Demand Media and Great Lakes Brewing News in 2010. Harris holds a Bachelor of Science in Mathematics from Penn State University; she taught high school math for several years and has also worked in the field of instructional design.
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4 How Does Climate Change Affect the Temperature in a Deciduous Forest?