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Rainfall Types

Rainfall Types

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Rainfall Types

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  1. Rainfall Types  Tom Abbott, Biddulph High School and made available through www.sln.org.uk/geography and only for non commercial use in schools

  2. Convectional Rain • During summer days the earth’s surface can becomes very hot. • This can cause an intense warming of the air making it very buoyant. • The air rises quickly. • As it does so it expands and cools. The air can no longer hold • the moisture; condensation takes place and rain forms. • The cool air then falls and • is caught and dragged back • upward by more rising air • forming a convection cell.  Tom Abbott, Biddulph High School and made available through www.sln.org.uk/geography and only for non commercial use in schools

  3. Negative Charge Cumulonimbus cloud Positive Charge Cool air descends and replaces warm air Lightning Movement of Storm  Tom Abbott, Biddulph High School and made available through www.sln.org.uk/geography and only for non commercial use in schools

  4. Frontal Rain • A warm air mass tries to force into a cold air mass. • The warm air is lighter and less dense than the cold air and so is forced to rise over it. • As the warm air rises it expands and cools and so rain forms.  Tom Abbott, Biddulph High School and made available through www.sln.org.uk/geography and only for non commercial use in schools

  5. Warm air rises over cold air; it expands and cools, condenses, clouds and rain form Warm air This line represents the front separating warm air from cold air Cumulus cloud Rain Warm air Cool air  Tom Abbott, Biddulph High School and made available through www.sln.org.uk/geography and only for non commercial use in schools

  6. Orographic (Relief) Rain • Upland areas force the warm moist air upward, where it cools. • As the warm air rises it expands and cools, condensation takes place and rain forms. • The rain is often heavy and prolonged.  Tom Abbott, Biddulph High School and made available through www.sln.org.uk/geography and only for non commercial use in schools

  7. When the air descends the pressure on it increases; the air contracts and warms When air rises the pressure on it decreases; the expands and cools Pressure decreases Pressure increases Rain Dry wind Moist wind Little or no rain Sea  Tom Abbott, Biddulph High School and made available through www.sln.org.uk/geography and only for non commercial use in schools