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8 Cards in this Set
- Front
- Back
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Latitude |
The lower the latitude, the higher the temperature. The angle of incidence of sun’s rays is higher at lower latitudes and hence receive a higher amount of heat as compared to higher latitudes The rays travel through a shorter distance and hence less solar radiation is lost through reflection, scattering and absorption. Thus the higher temperature. |
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Altitude |
The lower the altitude, the higher the temperature. The air is warmed by heat radiated from the warm ground and transferred by conduction and convection. It is much warmer at the lower ground because there is a larger area of land. Most of earth’s atmosphere concentrated at earth’s surface trap heat. Air under greater pressures of lower altitudes is denser and therefore warmer. |
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Proximity to the sea |
Water gains and loses heat much slower than land. Thus in winter, air over the sea is much warmer than over land, so winds from the sea bring heat to the coastal lands. In contrast, during summer coastal areas remain much cooler than their inland sites. |
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Cloud Cover |
A thick cloud cover reflects some of the incoming solar radiation so that land is not heated up excessively in the day. At night, the clouds prevent much solar radiation from escaping back to space, resulting in temperature decreasing by a few degrees. Hence the diurnal range is small, for example in equatorial area as compared to desert areas where cloud cover is thin. |
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Convectional Rain |
On a hot day, the air is in contact with the warm ground which is heated up by conduction. The warm air expands and becomes lighter than the surrounding air, so it becomes unstable and rises. This unstable air, which can hold a lot of moisture, rises in convectional currents. As it rises to a great height, it cools. Further cooling, after it is saturated at dew point, causes the water vapour to condense into water droplets. The water droplets coalesce to form cumulonimbus clouds.When the water droplets are too heavy to be suspended, convectional rain falls. |
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Relief Rain |
Onshore winds originated from the sea are moisture-laden winds. On reaching the land, they are blocked by mountain ranges which are relief barriers running parallel to the coast and hence are forced to rise. As air rises, it expands and cools and this leads to a rise in the relative humidity. Further rising and cooling after it is saturated at dew point will cause the water vapour to condense into water droplets. Water droplets aggregate to form clouds.When the water droplets in the cloud are too heavy to be suspended, relief rain falls on the windward side of the mountain. |
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Pressure |
Air pressure is the weight of the air exerted on any exposed surface. It is exposed in millibars. The air nearest to the ground has the highest pressure because of the weight of overlying air. There is less overlying air nearer the top of the atmosphere, so air pressure decreases with increasing height. Air pressure varies with temperature. Warm air expands, becomes less dense and rises, resulting in lower pressure below. Cold air, which is denser, sinks and exerts higher pressure below it. |
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Sea Breeze |
In the day, the coastal land is heated up faster than the sea. As the heated air expands and rises, a low pressure area forms over the land. Since the water is cooler, a higher pressure area forms over the sea. A sea breeze starts blowing from the higher pressure area over the sea to the lower pressure area over the land to replace the air that has risen. |
