By megan mcclay and abby schmidt World climate zones By megan mcclay and abby schmidt

BASIC CLIMATE GROUPS There are three basic climate groups. Group one has low-latitude climates, these climates are controlled by the equator. Group two has mid-latitude climates, the climates in this zone are affected by air masses being in constant conflict. Group three has high latitude climates polar and arctic air masses are the main ones in this region.

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Group one Low latitude climates

Tropical moist climates Rainforests are a good example of tropical moist climates. Annual rainfall is usually more than 100 inches with heavy rainfall year round. The temperature is around 80 F all year and humidity is between 77 and 88%. High surface heat and humidity form cumulus clouds early in the day nearly everyday.

WET-Dry tropical climates Seasonal changes occur between wet tropical air masses and dry tropical air masses. Therefore there is a very wet season and a very dry season. Trade winds dominate during dry seasons. It gets slightly cooler during this dry season but will become extremely hot just before the wet season.

Dry tropical climate These desert climates are found in low-latitude deserts. These latitude belts are centered on the Tropics of Cancer and Capricorn. They coincide with the edge of the equatorial subtropical high pressure belt and trade winds. Winds are light, which allows for the evaporation of moisture in the intense heat. They normally flow down so the area is barely ever hit by air masses that make rain. This makes for a very dry heat. The dry arid desert is a true desert climate. It covers 12% of the Earth’s land surface.

Group two Mid-latitude climates

Dry mid- latitude climate It has grasslands and is a semiarid climate. If it received less rain, the steppe would be classified as an arid desert. With more rain it would be a tall grass prairie. It is located in N. America and Eurasian continents. Moist ocean air masses are blocked by mountains to the west and south. There mountains also trap polar air in winter, making winters very cold. Summers are warm to hot.

Mediterranean climate This is a wet-winter, dry-summer climate. Very dry summers are caused by the sinking aid of the subtropical highs and may last for up to five months. Plants have adapted to the extreme difference in rainfall and temperature between winter and summer seasons. Plants range from forests, woodland and scrub. Fires are very common in this type of climate.

Dry mid-latitude climates These dry climates are limited to the interiors of N. America and Eurasia. Ocean air masses are blocked from this type of climate by mountains in the west and south. This allows polar air masses to dominate in winter months. In the summer, a local continental air mass is dominant. A small amount of rain falls during this season. Annual temperatures range widely. Summers are warm to hot, but winters are cold.

Moist continental climate This climate is in the polar front zone the battleground of polar and tropical air masses. Seasonal changes between summer and winter are very large, along with daily temperatures which change often. A lot of rain falls year round. It goes up during the summer because it invades tropical air masses. Cold winters are caused by polar and arctic masses moving south.

Group three High-latitude climates

Boreal forest climate This is a continental climate with long, very cold winters, and short, cool summers. This climate is found in the polar air mass region. Very cold air masses from the arctic often move in. The temperature range is larger than any other climate. Rain increases during summer months, but annual rain is still small. Much of this climate is considered humid, but large areas in western Canada and Siberia get very little rain and fall into the subhumid or semiarid climate type.

Tundra climate The tundra climate is found in arctic coastal areas. Polar and arctic air masses dominate the tundra climate. The winter season is long and brutal. A short, mild season exists, but not a true summer season. Moderating ocean winds keep the temperatures from being as severe as interior regions.

Highland climate Highland climates are cool to cold, found in mountains and high plateaus. Climates change rapidly on mountains, becoming colder the higher the altitude gets. The climate of a highland area is closely related to the climate of the surrounding biome. The highlands have the same seasons and wet and dry periods as the biome they are in. Mountains climates are very important to midlatitude biomes. They work as water storage areas. Snow is kept back until spring and summer when it is released slowly as water through melting.

Why Climates vary

Latitude The intensity of solar radiation decreases at altitude increases The sun is directly pointed closer to the equator and therefore it receives more radiation and is warmer You can tell by when you look into the sky and at certain points the sun appears in different places, in the arctic circle and Antarctic circle the sun either never sets or rises

altitude The higher the place, the colder it is Air temperature drops 3.5 degrees(F) every 1,000 feet of altitude The temperature determines how much precipitation, like snow, will fall Even in the tropics, mountaintops can be snowcovered

topography Surface features influence the climate, they can influence the development of clouds and precipitation amounts Warm humid air sweeps up the windward side of a mountain and as the air cools clouds form and creates precipitation The leeward slopes tend to be dry and Rain shadows may stretch for miles behind the mountain

Oceans and large lakes Ocean and lake surfaces warm and cool more slowly than land surfaces The temperature of the water influences the air above it, so the areas downwind of the body of water tend to have a milder climate San Francisco and St. Louis are about the same latitude, so they receive the same amount of solar radiation, but since San Fransisco is down wind of the Pacific Ocean it has milder winters and cooler summers

Atmospheric circulation Atmospheric circulation produces winds that distribute heat and moisture Due to the trade winds the climates are different in different areas because they create wind going in a certain direction and bringing influence from its origin with it

Factors that influence climate Short/long term

Volcanic eruptions volcanic eruptions cause more of a short term climate change Eruptions can cause there to be a short period of cooling in the air When sulfur gases combine with moisture they absorb some of the radiation from the sun and can also reflect the radiation, therefore less radiation reaches the surface creating a short period of a cooler climate This short period can be from a few days to even a few years The 1991 eruption of Mount Pinatube in the Philipines created a drop of 1.1 degrees(fahrenheit) for the folllowing couple of years

Ocean circulation Normally ocean circulation changes are short term- a few years The changes during El Nino can alter the climate for a few years El Nino is a change between the tropical atmosphere and oceans, changes in the air pressure over the Pacific can weaken the trade winds, or even make them change direction. When El Nino occurs then it changes the air and can create weather changes as well

CO2 concentration changes These can cause short and long term changes in the atmosphere and climate Atmospheric CO2 causes the greenhouse effect, where it will reflect and trap the radiation from the sun into the atmosphere Human activiy is increasing the CO2 levels in the atmosphere which causes fluctuations in the climate Also there is insight of volcanic activity on the ocean floor that released tremendous amounts of CO2 that occurred about 100 million years ago, so the earth also naturally goes through changes

Earth’s orbit Milutin Milankovitch proposed that there are three orbit variations that affect the sunlight distribution Precession(wobbling) of the earth’s axis Tilt changes Path of the orbit, changing Changes of these factors can influence the amount of solar radiation reaching different spots on the earth which creates climate changes, although these create short changes most of the time it is believed to be a cycle so the earth has gone through these climate changes in the past

Continental drift An extremely slow process that influences climate over millions of years As the continents move due to plate tectonics their climate changes This explains why there are tropical fossils found in Antarctica and ocean sediment and shells on the tops of mountains

Mountain building This is a very slow process in altering the climate It alters an areas altitude and changes the temperature The rise of the himalaya and colorado plateau may have happened within the past 10 million years and some scientists think that the rise of these massive landforms altered the wind belts, which made the earth’s climates more diverse

Human activity We alter the climate in more ways than one When we build cities, clear forests, and burn oil and other natural gases it can change the climate Cities have a warmer and drier area than the surrounding countryside Large urban areas affect the areas downwind of them because of the pollution including smoke and fuel gases Burning fossil fuels contributes to the rising CO2 amounts in the atmosphere Clearing forests reduces the rate at which CO2 is removed from the air because trees and other plants remove it during photosynthesis and emit oxygen Some climatologists say that there is a natural fluctuation of the temperature and that human activity isn’t contributing to global warming

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RESOURCES World book encyclopedia 2007 edition volume 9: H pages 676-679 www.blueplanetbiomes.org grc.k12.nf.ca http://www.buzzle.com/articles/tundra-climate-facts.html http://www.celsias.com/article/report-calls-global-climate-talks-consider-boreals/ http://explore.ecb.org/videos/VLC_media?P1=VLC033&REFERER=OTHER http://www.dask.org.tr/english/want_to_know/meteorology/climate/climate.htm http://www.ourplaceinfrance.co.uk/