Chapter 3 Section 3

   Geographers use information about the weather over many years to describe a climate region. The two most important factors in defining different climates are temperature and precipitation. They also use the location on a continent, topography, and elevation to help describe the climate.

   The most common characteristic used to define climate is latitude. There are five general climate regions based on latitude. They are tropical, dry, mid-latitude, high latitude, and highland. Within the regions there are variations.

   The tropical wet region has little variation in temperature over the year. It is always hot, with an average temperature of 80° F. The days begin sunny, but rain falls almost daily. The average amount of rain in a year is more than 80 inches.

    tropical wet and dry climate has a rainy season in summer and a dry season in winter. Temperatures are cooler in the dry season and warmer in the wet season. Rainfall is less than in the tropical wet climate region. It falls mostly in the wet season.

   A semiarid climate region does receive precipitation, just not very much. Generally areas receive about 16 inches per year. Summers are hot. Winters are mild to cold. Some semiarid locations can have snow. This climate region is found in the interior of continents or in the zone around deserts. Even though it is dry, the region contains some of the most productive agricultural lands in the world.

   Deserts are categorized according to the amount of rainfall. They can also be hot or cool/cold. Hot deserts have low humidity and high temperatures during the day. At night, temperatures drop because the dry air cannot hold heat well. Cool/cold deserts are found in the mid-latitudes in the Northern Hemisphere.

   The Mediterranean climate zone is named for the land around the Mediterranean Sea. Its summers are dry and hot, and its winters are cool and rainy. This climate region supports a dense population and rich agricultural activity.

   The marine west coast climate region is frequently cloudy, foggy, and damp. The winds that blow over the warm ocean water keep the temperatures warm. Precipitation in this climate region is evenly distributed throughout the year.

   A great variety in temperature and precipitation characterizes the humid continental climate region. It is found in the mid-latitude interiors of Northern Hemisphere continents. Air masses chilled by Arctic ice and snow flow south over these areas. They collide with tropical air masses coming from the south. This causes changing weather conditions. These areas experience four seasons.