Earth Science: Atmosphere – Climate of the Temperate Zone
The temperate zone covers the Northern and Southern Hemispheres between 45° latitude and the polar circle at 66.5° latitude. It can be divided into a cool and a cold temperate zone.
The temperate zone mainly depends on the westerly winds outside the tropics which bring a maritime climate to coastal areas while inland areas experience a continental climate with decreasing annual precipitation. The average annual precipitation is around 31 inches. Overall, there are distinct seasons, slightly less so toward the Equator.
Another typical characteristic is the variation of night and day hours according to the season. This variation increases with decreasing distance to the Poles. The Gulf Stream has a significant effect on the climate in central and northern Europe which would be much colder without the influence of this ocean current.
The cool temperate zone
In the Northern Hemisphere, the warm temperate zones are located on the west coast and in the northeast of North America as well as in large parts of Europe and East Asia. In the Southern Hemisphere, they are located in Chile, southeast Australia, Tasmania, and the southern island of New Zealand.
The average annual temperature is between 46.4 and 53.6°F (8 and 12°C). The actual temperatures in the coastal areas are milder with a maritime climate where monthly aver- age temperatures hardly fall below freezing while the continental inland temperatures are very high in summer and very low in winter.
The dryness of the continental climate of the temperate grasslands makes tree growth impossible. In contrast, deciduous forests with oaks, beech, hornbeam, birch, and ash trees are common in areas influenced by the maritime climate.
The cold temperate zone
If the growth period decreases to less than 120 days due to cold temperatures, deciduous woods have no chance of survival. Coniferous forests are therefore wide- spread in the cold temperate zones closer to the Poles. About 10 percent of this continental area is taken up by the taiga with vast swamp and raised moss areas. In the Northern Hemisphere, this type of vegetation is the most widespread.
In the Southern Hemisphere, such vegetation is almost entirely absent due to the distribution of land and ocean. The average temperature of the coldest month is below 26.6°F (-3°C) and below -13°F (-25°C) in the coldest areas. The warmest month reaches on average less than 50°F (10°C).
The boundary between continental and hot summer continental climate is where temperatures fluctuate by more than 104°F (40°C). Precipitation falls as rain in the summer and as snow in the winter.
BASICS
CONTINENTAL CLIMATE differs from maritime climate where daily and annual temperature fluctuations are less extreme. This is due to the heat storage capacity of the oceans: Although the ocean heats up more slowly than the ground during summer, it also cools down more slowly and releases the stored heat during winter.
With increasing distance from the coasts there is also a significant reduction in annual precipitation.