World Climates

Climate is the characteristic condition of the atmosphere in the lower layer of Earth’s atmosphere. It is based upon the long- term weather in an area accumulated over a period of at least 30 years. Two of the most important factors used in determining the climate of an area are the air temperature and the amount of precipitation received.

The climate of a region will determine which types of plants will grow as well as what kind of animals will be there. The angle of the sun’s rays is most direct from 0° to 23.5° making that area the hottest. The angle of the sun’s rays are least direct from 66.5° to 90° making that the coldest area on Earth. In the middle are the more moderate temperatures which vary more with season.

Trade winds are located in the tropical regions blowing from the northeast in the northern hemisphere and from the southeast in the southern hemisphere. The trade winds meet at the equator and rise as the air is heated. The rising air cools, forms clouds and creates precipitation. The bands of cloudy and rainy weather near the equator create what we know as normal tropical conditions.

In the mid-latitudes (30°- 60°) the Westerlies steer the storms from west to east. Our climate is based upon the location of the hot and cold air masses as well as the atmospheric circulation caused by the Trade Winds and the Westerlies.

Seasons Seasons are the result of Earth’s tilt on it’s axis 23.5°; the fact that Earth revolves around the Sun and that the tilt of Earth on it’s axis remains parallel throughout it’s revolution. As a result different parts of Earth receive higher and lower levels of radiant energy at different times of the year creating the seasons

Climate Classification The Koeppen Climate Classification System is the most widely used for classifying the world’s climates. It was created by the Russian-German climatologist Wladimir Koeppen who divided Earth’s surface into climatic regions that matched the world patterns of vegetation and soils.

Five Major Climate Types Moist tropical Climates Dry Climates Humid/Middle Latitude Climates Continental Climates Cold Climates

Moist Tropical Climates known for their high temperatures year round and for their large amount of rain year round

Dry Climates characterized by little rain and a huge daily temperature range. Two sub-groups:  semiarid or steppe  arid or desert

Humid Middle Latitude Climates Land/water differences play a large part These climates have warm, dry summers and cool, wet winters

Continental Climates can be found in the interior regions of large land masses total precipitation is not very high and seasonal temperatures

Cold Climates These climates are found where permanent ice and tundra are always present Only four months of the year have above freezing temperatures

Three basic climate groups The major climate groups show the dominance of special combinations of air mass source regions: Low Latitude Climates Mid-latitude climates High latitude climates

Low latitude climates are controlled by equatorial tropical air masses.  Tropical Moist Climates – rainforest  Wet-Dry Tropical Cimates – savanna  Dry tropical Climate – desert biome

Mid-latitude climates are affected by tropical and polar air masses. Dry Mid-latitude Climate – steppe Mediterranean Climate – chaparral Dry Mid-latitude Climate – grasslands Moist Continental Climate – deciduous forest

High Latitude Climates are dominated by polar and arctic air masses. Boreal forest Climate – taiga Tundra Climate – tundra Highland Climate – alpine Polar Ice Cap – cold desert

Tropical Moist Climate- rainforest  Rainfall is heavy in all months. The total annual rainfall is often more than 250 cm (100 in). There are seasonal differences in monthly rainfall but temperatures of 27  C (80  F) mostly stay the same. Humidity is between 77% and 88%. Summers are warm and very humid. It rains a lot in winter.  Latitude Range: 10  S to 25  N  Global Position: Amazon Basin; Congo Basin of Equatorial Africa; East Indies from Sumatra to New Guinea

Tropical Moist Climate- rainforest

Wet-dry Tropical Climates - savanna A seasonal change occurs between wet tropical air masses and dry tropical air masses. As a result, there is a very wet season and a very dry season. Temperature ranges around 16  C. The annual precipitation in all months is less than.25cm (.01 in). Latitude Range: 15  to 25  N and S Global Position: India, Indochina, West Africa, southern Africa, South America and the north coast of Australia

Wet-dry Tropical Climates - savanna

Dry Tropical Climates - desert These climates are found in low latitude deserts between 18  to 23  in both hemispheres centered on the tropics of Cancer and Capricorn. Winds are light allowing for the evaporation of moisture in the intense heat. Air sinks so the area is seldom penetrated by air masses that produce rain creating a very dry heat. The temperature ranges around 16  C. Annual precipitation is less that 0.25cm (0.1 in). Latitude Range: 15  to 25  N and S Global Position: southwestern United States; northern Mexico; Argentina; north Africa; south Africa; central part of Australia

Dry Tropical Climates - desert

Mid Latitude Climates Climates in this zone are affected by the tropical air masses moving toward the poles and polar air masses moving toward the equator. These two air masses are in constant conflict. Either air mass may dominate the area for a time, but neither has exclusive control.

Dry Mid-latitude Climates - steppe This is a semi-arid climate with less than 10 cm (4 in) annual precipitation in the driest regions to 50 cm (20 in) in the moister areas. Latitude Range: 35  - 55  N Global Position: Western North America (Great Basin, Columbia Plateau, Great Plains); Eurasian interior, from eastern Europe to the Gobi Desert and north China

Dry Mid-latitude Climates - steppe

Mediterranean Climate - chaparral This climate has a wet winter and an extremely dry summer. Plants have adapted to the extremes in rainfall and temperature during the summer and winter seasons. Plants range from forests, to woodland, to scrub. Temperature range is 7  C (12  F) with 42 cm (17 in) of precipitation. Latitude Range: 30  - 50  north and south Global Position: central and southern California; coastal zones bordering the Mediterranean sea; coastal western Australia and southern Australia; Chilean coast; Cape Town region of South Africa

Mediterranean Climate - chaparral

Dry Midlatitude Climate - grasslands This climate is limited to the interiors of North America and Eurasia. Ocean air masses are blocked by mountain ranges to the west and south allowing polar air masses to dominant winter and local air masses to dominant summer. The temperature range is 31  C (56  F) and average precipitation is 81 cm (32 in). Latitude Range: 30  - 55  N and S Global Position: western North America (Great Basin, Columbia Plateau, Great Plains; Eurasian interior

Dry Midlatitude Climate - grasslands

Moist Continental Climate – deciduous forest This climate is the battleground of polar and tropical air masses. Seasonal changes between hot summers and cold winter are very large. Precipitation varies from 40 to 60 in per year. The average temperature is 31  C (56  F) Latitude Range: 30  - 55  north and south Global Position: eastern parts of the United States and southern Canada; northern China; Korea; Japan; central and eastern Europe

Moist Continental Climate – deciduous forest

High Latitude Climates Polar and arctic air masses dominate these regions. Canada and Siberia are two air-mass sources which fall into this group. There is no counterpart in the southern hemisphere since the largest land masses are in the northern hemisphere.

Boreal Forest Climate - taiga This is a continental climate with long, very cold winters and short cool summers. The temperature range is the greatest from -25º C (-14º F) to 16º C (60 º F) with the annual precipitation at 31cm (12 in). Latitude Range: 50º - 70º north and south Global Position: central and western Alaska; Canada from the Yukon to Labrador; Eurasia, from northern Europe across all of Siberia to the Pacific Ocean

Boreal Forest Climate - taiga

Tundra Climate - tundra This climate is found along arctic coastal areas. The arctic air masses dominate the area but ocean winds keep temperatures from being as severe as interior regions. The winter is long and severe. There is a short mild season but not a true summer. Temperatures range from -22º C to 6º C (-10º - 41º F). Average precipitation is 20 cm (8 in). Latitude Range: 60º - 75º N Global Position: arctic zone of North America; Hudson Bay Region; Greenland coast; northern Siberia bordering the Arctic Ocean

Tundra Climate - tundra

Highland Climate - alpine Highland climates are cool to cold found on mountains and high plateaus. The temperature cools rapidly as the altitude gets higher. These climates are very important to mid latitude climates since they are a storage area for water in the form of snow which melts in the spring. Temperatures range from -18º -10º C (-2º - 50º F) and precipitation averagea 23 cm (9 in). Latitude Range: All over the world Global Position: Rocky Mountain Range in North America; the Andean mountain range in South America; the Alps in Europe; Mt. Kilimanjaro in Africa; the Himalayans in Tibet; Mt. Fuji, Japan.

Highland Climate - alpine

Polar Ice Cap – cold desert This region is permanently frozen with no temperatures above 32º F. Precipitation is very low but varies from region to region. Latitude Range: 60º - 90º N and S Location: Arctic; Antarctica; Greenland

Polar Ice Cap