Climate describes the average yearly conditions of temperature, precipitation, wind, and cloud cover in a particular region. The climate of an area is mainly determined by temperature and precipitation. Several factors influence temperature, including latitude, altitude, large bodies of water such as lakes and oceans, ocean currents, and the distance of land areas from these bodies of water. Precipitation is influenced by prevailing winds, mountain ranges, and seasonal wind patterns, which vary across hemispheres as each hemisphere receives different amounts of solar energy throughout the year. A microclimate is a small area where climate conditions differ from those of the surrounding region.

Earth’s surface is divided into three main temperature zones based on latitude. The tropical zone, located near the equator, receives direct sunlight year-round and therefore has a warm climate. The polar zones are much colder because the Sun’s rays strike the surface at a lower angle. Between these regions are the temperate zones, where temperatures vary from warm summers to cold winters.

Altitude plays an important role in determining temperature. As altitude increases, air temperature generally decreases. This is why higher elevations tend to have cooler climates than nearby lowlands. Large bodies of water also influence temperature because water heats and cools more slowly than land. Areas near oceans or large lakes often have marine climates, characterized by relatively mild temperatures, warm winters, and cool summers. In contrast, inland regions often have continental climates, which are characterized by colder winters and warmer or hotter summers.  Ocean currents further influence climate by warming or cooling the air above them. As winds move this air toward land, they can bring warmer or cooler conditions to nearby coastal regions.

In addition to temperature patterns, several processes influence how precipitation is distributed across Earth. Prevailing winds carry warm, moist air or cooler, drier air across the land. When these winds encounter mountain ranges, the mountains influence where precipitation falls. Air rising on the windward side of a mountain cools and releases moisture as precipitation. The opposite side of the mountain, called the leeward side, receives much less rainfall and may form a rain shadow, an area of low precipitation. Seasonal wind patterns can also influence precipitation. In some regions, large-scale seasonal wind shifts known as monsoons bring wet and dry seasons as winds change direction between land and sea.

Review:

1. What two factors determine the climate of a region?
2. What is a microclimate?
3. What factors affect precipitation?