Influence of Topography on Climate

  1. The distribution of land, seas, mountain ranges, valleys and other features influences regional climates.
  2. Large bodies of water will :
    1. Moderate temperatures due to the high specific heat of H2O.
    2. Specific heat: amount of heat added or removed from 1 g of a substance to change its temperature by 1°C.
    3. Water is slow to warm up (cools hot air) and slow to cool off (warms cold air).
    4. Provide a source of moisture for the air, precipitation tends to be higher.
  3. Near the center of a land mass :
    1. Temperatures are more extreme (very hot or cold).
    2. Precipitation tends to be lower (no water sources).
    3. Differential heating / cooling: refers to the land heating or cooling at a faster rate than water bodies.
  4. Elevation changes:
    1. Denser air can contain more heat energy.
    2. Temperatures decrease as elevation increase (this is separate effect from adiabatic cooling).
  5. Near mountains, adiabatic processes (AP) are important :
    1. Adiabatic processes: a thermal process that occurs without the transfer of heat.
    2. If a gas expands adiabatically (such as a parcel of air going up a mountain slope), the temperature decreases.
    3. If a gas compresses adiabatically (such as a parcel of air coming down a mountain slope), the temperature increases.
    4. AP change air temperatures as air moves over the mountains. Temperatures on the windward side (side facing the wind) of mountains are cooler than on the leeward side (side away from the wind).
    5. AP affect where clouds form. Precipitation is higher on the windward side of mountains with a rain shadow on the leeward side.
      1. As air approaches the mountains (windward side), it rises to go over them.
      2. As it rises, it expands and cools to the point where the air can not hold water vapor anymore
      3. This is called the dew point and clouds form. Precipitation occurs.
      4. Most of the moisture is taken out of the air by the time it gets over the mountain summits.
      5. As the air descends down the mountain's leeward side it compresses and warms
      6. The warming air absorbs moisture from the ground and dries the leeward side.
  6. Diagrams: