2.4. Factors Affecting Climate

Latitude: Due to the earth's inclination, the mid-day sun is almost overhead within the tropics but the sun's rays reach the earth at an angle outside the tropics. Thus, temperature diminishes from equatorial regions to the poles.

Altitude: Earth’s atmosphere is mainly heated through conduction from the surface, so places near the surface are warmer than those higher up. Thus temperature decreases with increasing height above sea level. This rate of decrease in temperature with altitude (lapse rate) is never constant, varying from place to place and from season to season. However, for all practical purposes, it may be reckoned that a fall of 6.5°C occurs with an ascent of 1000 meters or 1oC per 165 meters.

Continentality (Distance from sea): Land surfaces have higher specific heat capacity of heat as compared to water bodies i.e. it takes less energy to raise the temperature of a given volume of land by 1oC as compared to same volume of water body. This accounts for temperature extremes in the continental interiors as compared to maritime areas.

Oceans Currents: Marine areas are influenced by the warm or cold ocean currents. Ocean currents like the Gulf Stream or the North Atlantic Drift warm the coastal districts of Western Europe keeping their ports ice-free. Ports located in the same latitude but washed by cold currents, such as the cold Labrador Current off north-east Canada, are frozen for several months. Cold currents also lower the summer temperature, particularly when they are carried landwards by on-shore winds.

Local winds: If winds are warm i.e. they have been blown from a hot area, they will raise temperatures. If winds have been blown from cold areas, they will lower temperatures. Local winds like Fohn, Chinook, Sirocco and Mistral also produce marked changes in temperature.

Relief and Topography: Climate can be affected by mountains. Mountains receive more rainfall than low lying areas because as air is forced over the higher ground it cools, causing moist air to condense and fall out as rainfall. The higher the place is above sea level the colder it will be. This happens because as altitude increases, air becomes thinner and is less able to absorb and retain heat.

Latitude

Human

Influence

Altitude

ElNino

Slope, Shelter & Aspect

Factors

Affecting Climate

Contineta

lity

Ocean

Current

Natural

Vegetation

Relief &

Topography

Local

Winds