Earth Science 21.1 Climate

1. Earth Science 21.1 Climate Climate

2. Earth Science 21.1 Climate • Recall from our earlier chapter that climate involves not only the average weather conditions of an area but also any variations from the normal conditions. • In this chapter we will examine climate and view the complex relationships between • the atmosphere, • the energy from the sun, • the moisture in the atmosphere, • the global wind patterns, • and the effect of man and industrialization of on all of this.

3. Earth Science 21.1 Climate Factors that Affect Climate • The varied nature of Earth’s surface and the many interactions that occur between Earth’s biospheres give every location on Earth a distinct climate. We will examine how • latitude, • elevation, • topography, • large bodies of water, • global winds, and • Vegetation affect the two most important elements of climate; temperature and precipitation.

4. Earth Science 21.1 Climate Latitude: • Latitude is the distance north or south of the equator. • The greater the latitude, the farther away from the Earth’s equator and the closer to the Earth’s polar regions. • As latitude increases, the average intensity of solar energy decreases. • Near the equator, the sun’s energy strikes the Earth at nearly right angles passing through less atmosphere. • The amount of sunlight per square inch is greatest at this point because of the direct angle of the incoming sunlight.

5. Earth Science 21.1 Climate Latitude: • This region of the Earth; between 23.5 degrees north and 23.5 degrees south, is called the tropical zone or “The Tropics”. • In this tropical zone the sun’s rays, and therefore the amount of energy delivered by sunlight, is the greatest. • Because of this, temperatures in the tropical zone are generally warm year round. • Many of the world’s most famous resort areas are found within this Tropical zone; such as Acapulco Mexico, Costa Rica, or the Caribbean islands.

6. Earth Science 21.1 Climate Latitude: • The next zones directly above and below the tropical zones are called the temperate zones. • The temperate zones exist between 23.5 degrees (Tropic line) latitude (north and south) and 66.5 degrees (Polar Circle latitude (north and south). • Where we live in New England is in the middle area of the Northern temperate zone.

7. Earth Science 21.1 Climate Latitude: • In the temperate zones, the sun’s light strikes Earth at an oblique angle spreading the rays out over a larger surface area. • In addition, the length of the days is much longer in the summer than in the winter. • As a result, temperate zones have hot summers and rather cold winters.

8. Earth Science 21.1 Climate Latitude: • In the polar zones, which are between 66.5 north and south latitudes and the poles, the energy from the sun strikes at an even smaller angle causing the light and heat to spread out over an even larger area. • Because of this, the polar regions experience cold temperatures , even in the summer months.

9. Earth Science 21.1 Climate Latitude: • Because of the effect of latitude, less solar energy per unit of area is transferred into the atmosphere in the polar regions as compared to the tropics. • This difference in energy effects weather and climate from the equator to the poles. • These differences in energy lead to the pressure differences that produce winds. • Differences in energy affect evaporation rates and the formation of clouds, air masses, and storms. • Over time, energy differences on a global scale also determine climate.

10. Earth Science 21.1 Climate Elevation: • Elevation, height above sea level, affects an areas climate. • Air temperature decreases with elevation by an average of about 6.5 degrees (Celsius) every 1000 meters. • The higher the elevation is, the colder the climate. • The elevation of an area also determines the amount of precipitation it gets.

11. Earth Science 21.1 Climate Topography: • Topographical features such as mountains play an important role in the amount of precipitation that falls over an area. • Humid air on a windward side of a mountain moves up the mountain’s slope, cooling in the process to form clouds. • Heavy rains often fall from these clouds. • By the time the air reaches the far side of the mountain (leeward side) much of the moisture has been lost. This dry area is called the rain shadow. • Rain shadows can extend for hundreds of kilometers downwind of a mountain range.

12. Earth Science 21.1 Climate Water Bodies: • Large bodies of water such as lakes and oceans have an important effect on the temperature of an area. • This is because the temperature of the water body influences the temperature of the air above it. • Places downwind of a large body of water generally have cooler summers and milder winters than places at the same latitude that are farther inland. • Places downwind from large lakes, such as the Great Lakes, also feel the Lake Effect as prevailing wind currents carry moisture across the lakes to drop as snow on the far sides.

13. Earth Science 21.1 Climate Atmospheric Circulation: • Global winds are another factor that influences climate because they distribute heat and moisture around the Earth. • Recall from our previous lesson (Ch 19) that winds constantly move warm air toward the poles and cool air toward the equator. • The low pressure zones at the equator and in the middle latitudes lead to the formation of clouds that drop precipitation as rain and snow.

14. Earth Science 21.1 Climate Vegetation: • You already know that the type of plants that grow in a climate are largely because of the type of climate. But did you know that the vegetation also affects the climate? • Vegetation can affect both temperature and the precipitation patterns of an area. • Vegetation controls how much of the sun’s energy gets absorbed and how quickly the energy is released. • This affects the temperature of a region.

15. Earth Science 21.1 Climate Vegetation: • How much energy a region’s vegetation absorbs and releases effects not only temperature, it also effects the amount of humidity in a region. • During a process called transpiration, plants release water vapor from their leaves into the air. • This water vapor increases the saturation level of the air which leads to rainfall eventually. • Studies also show that some plants release small particles which act as cloud seeds. • This increase in particles, such as pollen, promotes the formation of clouds which also effects an areas precipitation patterns.