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| An arial view of Costa Rica's coast line. |
Due to Costa Rica’s
diverse terrain and proximity to the equator (8°-11°N), its climate is famous for
a variety of microclimates (variations in weather and temperature). According to the Köppen classification Costa Rica
is of the Tropical Climate zone, specifically of the Tropical Rainforest Climte
(Af) in the rainforests and high
elevation regions, and of the Tropical wet and dry, or Savanna Climate (Aw), in the lower elevation regions of
the country.
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| A map Costa Rica's Köppen Climate Classification Zone |
The climate transitions between low land and mountain sites in
terms of ambient air temperature (temperature on a thermometer, not including
factors of humidity or wind), and transitional between the Caribbean and
Pacific sides of Costa Rica in terms of incident solar radiation (radiation
hitting a specific area) and seasonality of precipitation.
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| A map of Costa Rica's annual rainfall. |
Average
temperature in Costa Rica ranges from 63°-86°F and has a relative humidity average of
68.2%. Because the climate is dominated by the Intertropical Convergence Zone
[ITCZ] (a low-pressure area around the equator where the prevailing winds are calm), there are virtually no natural season. Costa
Rica has a dry season (December-April) and a rainy season (May-November). The map below shows Costa Rica's annual rainfall.
The two most important factors in Costa Rica’s weather are (1) the fairly even amount of solar radiation received, as the air temperature is a result of solar radiation and movements of the atmosphere at a given point; and (2) the northeasterly winds (named after the direction in which the wind is blowing), or trade winds known as “alisios.”
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| In this photo, we see the result of northeasterly winds and the production of rain along the Costa Rican Coastline. |
The adiabatic process of interaction
between the trade winds and Costa Rican topography leads to rainfall. As moisture-laden
air comes off the Caribbean Sea and meets the coastline, the difference in
temperature between the land and water triggers showers. As the wind moves in
and reaches mountains and foothills, the air mass (where atmosphere has high pressure allowing air to ‘absorb’ the temperature
and humidity characteristics of the surfaces) rises and cools, thus
rainfall (cooler air holds less moisture than warm air).
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