CHAPTER 7 NOTES“CLIMATE”SECTION 1: “WHAT IS CLIMATE?”Weater and climate differ because of time.Weather is the condition of the atmosphere at a particular time and place. For instance: What is the weather going to be like this week in Memphis?Climate is the average weather conditions in an area over a long period of time. The climate of Memphis is mild temperatures with lots of humidity.Climate is determined by 2 factors: temperature and precipitation.Climates differ for a number of reasons:1. Latitude2. Wind patterns3. Geography4. Ocean currentsLatitude:-latitude is the distance north or south, measured in degrees, from the equator.-The higher the latitude, the colder the climate. The North Pole is at 90 degrees North latitude and is one of the coldest places on Earth. The Equator is at 0 degrees and is one of the warmest.-The reason why there is a difference in temperature at the different latitude lines is because of the solar energy received from the sun at each latitude line. The sun’s rays hit the Earth at a 90 degree angle at the Equator causing this area to be the warmest. At the poles, the sun’s rays hit at a lesser angle creating less solar energy and a cooler climate.-Latitude also affects the seasons.-Land located on the equator or by the equator experience the same temperatures year round and the same amount of daylight year round because of the direct rays of the sun.- Because Earth is tilted on its axis at a 23.5 degree angle, the amount of solar energy an area recieves at a particular time is different from other regions on Earth.-During the winter months, the Southern Hemisphere has higher temperatures and longer days because it tilts toward the sun and recieves direct solar energy. The Northern Hemisphere has lower temperatures and shorter days because it tilts away from the sun.-During the summer months, the Northern Hemisphere is tilted toward the sun and receives direct solar energy and has longer days. The Southern Hemisphere has shorter days and colder temperatures because the solar energy is less since this area is tilted away from the sun.Prevailing Winds-These are winds that blow mainly in one direction and influence an area’s moisture and temperature.-Just like water, cold air sinks and warm air rises. As cold air sinks it will warm up. As it is heated, it is able to hold water vapor. As this warm air rises, it will cool down and lose its ability to hold water vapor and precipitation will occur. This is an ongoing cycle on Earth. This is why it is usually cooler after it rains.- Prevailing winds affect the amount of precipitation a region recieves. If the winds form from warm air, they will carry moisture. If they form from cool air, they will be dry. Memphis’ prevailing winds come from a warm area so we get more rain.-The amount of moisture a prevailing wind carries is also affected by whether it blows across land or water. Winds blowing over bodies of water absorb moisture. Winds that travel across land tend to by dry. Our winds usually cross the Mississippi River which creates moisture in our air.Geography-Mountatins can iinfluence an area’s climate. Mountains affect the temperature and precipitation of an area. Kilimanjaro, the tallest mountain in Africa has snow-covered peaks year-round even though it is located at 3 degrees south of the equator. This is due to elevation.-Elevation is the height of surface landforms above sea level. As the elevation increases, the atmosphere becomes less dense which decreases its ability to hold thermal energy and absorb it. Therefore, the temperatures are lower.-Mountatins also affect precipitation. Mountains can block the prevailing winds from blowing across a continent changing the amount of moisture the wind carries.Mountains force air to rise. The air cools as it rises and releases moisture as snow or rain. The land on this side(the windward side) is usually green and lush due to the amount of moisture. The other side of the mountain has dry air crossing over it. This air begins to sink and warm up by absorbing moisture. The dry conditions created by the sinking, warm air usually produce a desert. THis side is in a rain shadow.Ocean Currents-Surface currents which can be either warm or cold, are streamlike movements of water that occur at or near the surface of the ocean. As the surface currents travel they affect the temperature of the atmosphere above it. If the surface current is warm, the air above it will be warm. If the surface current is cool, the air above it will be cool.SECTION 2: CLIMATES OF THE WORLD3 Major climate zones of the Earth:1. Tropical2. Temperate3. Polar-Each zone has a temperature range that relates to its latitude. Each zone also has several climates due to the geography and the amount of precipitation in that area. Because of the different climates in each zone, the zones are broken down into biomes.-A biome is a large region characterized by a specific type of climate and the plants and animals that live there.The Earth’s Land Biomes are:1. Tundra2. Taiga3. Temperate forest4. Tropical rain forest5. Temperate grassland6. Tropical savanna7. Temperate desert8. Tropical desert9. Chaparral10. MountainsTROPICAL ZONE-Also known as the Tropics is the warm zone located around the equator. This zone extends from the Tropic of Cancer to the tropic of Capricorn. Because this zone recieves the most solar radiation, temperatures in this zone are usually hot, except at high elevations.-3 biomes in this zone: tropical rain forest, tropical desert, and tropical savanna.Tropical rain forest-Always warm and wet-Receive strong sunlight year round, causing little difference between seasons.-Contain the greatest number of plant and animal species of any biome.-The soil in the rain forest is very poor because of the rapid decay of animals and the nutrients are quickly absorbed in the soil and the plants take in all the nutrients. The nutrients not quickly absorbed are washed away by the heavy rains.Tropical Desert-Receives less than 25 cm or rainfall a year.-Driest place on Earth.-plants have adapted to surviving with little water.-They are divided into hot and cold deserts.-The majority of hot deserts are tropical deserts.-Caused by sinking cool air.-The temperature varies from hot daytime temperatures to cool nighttime temperatures.-Winters are usually mile.-The soil is poor in organic matter due to the dryness.-The dryness makes it hard to break down dead organic matter.Tropical Savannas-Sometimes called grasslands-Dominated by tall grasses, with trees scattered about.-Climate is usually very warm, with a dry season that lasts 4-8 months followed by short periods of rain.-Soils are generally nutrient poor, but grass fires, which are common during the dry season, leave the soils nutrient enriched.-Many plants use the fires to reproduce by sprouting from the roots after the upper part has been burned. The seeds of some depend on the fire to grow.TEMPERATE ZONE-the climate zone between teh Tropics and the polar zone.-Temperatures are moderate-Includes 4 biomes:1. Temperate forests2. Temperate grasslands3. Chaparral4. Temperate desertsTemperate Forests-Have very high amounts of rainfall and seasonal temperture differences.-Summers are usually warm and winters are usually cold.-The largest are deciduous which are trees that lose their leaves when the weather becomes cold. They tend to be broad-leaved.-The soils in decidiuous forests are usually fertile because of the high organic content given by the decaying leaves that drop every winter.-Evergreen forests consist of evergreen trees that keep their leaves year-round. They can be broad leaved or needle leaved trees. Pine trees are evergreens.-Mixed forests of evergreen and deciduous are found in humid climates such as Florida where winder temperatures rarely fall below freezing.Temperate Grasslands-Occur in regions that have too little rainfall for trees to grow.-Has warm summers and cold winters.-Also known as the prairies of North America and the steppes in Eurasia or the veldt in Africa and the pampas in South America.-Grasses are the most common type of vegetation found.-Have the most fertile soil of all the biomes so this biome is usually plowed and used for croplands.Chaparrals-Have cool, wet winters and hot, dry summers.-Vegetation is mainly evergreen shrubs, which are short, woody plnats with thick waxy leaves. These leaves are adaptations that help prevent water loss in dry conditions.-The shrubs grow in rocky nutrient-poor soil.-This vegetation has also adapted to fires.Temperate Deserts-Cold Desert-Receive less than 25 cm of rainfall a year.-Very hot in the daytime, but they tend to be very cold at night.-The temperatures sometimes drop below freezing.-This large change in temperature is due to low humidity and cloudless skies.-These conditions allow for a large amount of energy to reach the Earth’s surface during the day , but release it all at night.-Receive light snow during the winter.-Usually located inland or on the rain-shadow side of a mountain range.
