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Climate Determines Global Patterns in the Biosphere 34.2.

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Presentation on theme: "Climate Determines Global Patterns in the Biosphere 34.2."— Presentation transcript:

1 Climate Determines Global Patterns in the Biosphere 34.2

2 Uneven Heating of Earth’s Surface  Energy from the sun warms Earth's surface. But because of Earth's spherical shape, different locations on Earth's surface receive different amounts of solar energy.  Near the equator, the sun's rays strike the surface most directly.

3  Earth's surface can be divided into different temperature zones based on lines of latitude.  The region that lies between 23.5° N latitude (the Tropic of Cancer) and 23.5° S latitude (the Tropic of Capricorn), called the tropics, is the warmest temperature zone. tropics

4  The region north of the Arctic Circle (66.5° N) and the region south of the Antarctic Circle (66.5° S), called the polar zones, receive the least amount of direct sunlight year-round. polar zonespolar zones  The polar zones are the coldest temperature zones.

5  The latitudes in between the tropics and the polar zones in each hemisphere are called the temperate zones. temperate zonestemperate zones  Most of the United States is located within the northern temperate zone.

6 Wind, Precipitation, and Ocean Currents  The uneven heating of Earth's surface by the sun is also a driving force behind global patterns of winds and precipitation (rain, snow, and sleet).  When air is warmed it can absorb more moisture, and it also tends to rise.

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8  Thus air near the equator, heated by the direct rays of the sun, absorbs moisture and rises.  Higher in the atmosphere the air cools again, forming clouds that produce rainfall.  This pattern means that many areas of Earth close to the equator tend to have warm temperatures and heavy rainfall year-round.

9  After losing moisture over the equator, air masses spread away from the tropics.  The dry air descends again and warms at latitudes of about 30° N and 30° S.  Some of the world's largest deserts are found in these regions.

10  The rising and falling of air masses, combined with Earth's rotation, produce predictable wind patterns.  These wind patterns combine with the uneven heating of Earth's surface, the rotation of the Earth, and the shapes of the continents, producing surface currents.  A current is a river-like flow pattern within a body of water. current

11  Surface currents can greatly affect regional climates.  For instance, the Gulf Stream carries warm water northward from the tropics.  This makes the climate in western Europe warmer than other areas at similar latitudes.

12 Local Climate  On an August day, people in Los Angeles' San Fernando Valley might face temperatures of 38°C (100°F), while just 30 kilometers away, people at the beach are enjoying the comfortable 24°C (75°F) outdoor air.  Local climate variations may be influenced by nearby large water bodies.  Oceans and large lakes affect climate because water tends to absorb and release heat more gradually than most other substances

13  Mountains also affect local climate. First, air temperature declines by about 6°C with every 1000-meter increase in elevation.  This is why it becomes cooler as you hike up a mountain.  Second, mountains near a coast can block the flow of cool, moist air from the ocean, causing different climates on opposite sides of the mountain range.

14 Microclimate  Organisms living in the same climate region may be exposed to different conditions created by shade, snow cover, or windbreaks.  Such small-scale differences in climate result in a microclimate, the climate in a specific area that varies from the surrounding climate region. microclimate


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