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31 Cards in this Set
- Front
- Back
What is the starting point of rainfall? |
It is a cool atmosphere to allow condensation to occur |
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What causes precipitation? |
When clouds become over saturated, they are too heavy
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Why are there three types of rainfall? |
There are three types since the mechanism of rising air to cool the atmosphere differs |
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How is orographic / relief rain formed and give an example? |
When the location of a mountain forces air to rise and cool. Example: Drakensberg |
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Define windward / leeward slope |
It is when the air is forced the rise, condense and rain. The rain will only fall on the windward slope |
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What is 'the rain shadow'? |
The rain shadow is when the precipitation of windward slopes fall on the interior side; causing it to warm and evaporate. |
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What holds more moisture and less rain? |
The rain shadow |
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Define convection rainfall |
Occurs often during summer when convection currents cause air to cool and strong drought up currents that produce thunder and lightning |
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Define cyclonic / frontal rainfall |
Forms when incoming cold heavy air wedges beneath warmer air and forces it to rise and cool adiabatically SOFT, PROLONGED SHOWER IN WINTER |
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Give three ways of measuring rainfall |
1. Tipping bucket (gives intensity of rain) 2. Rain Gauge (cylinder that captures rain) 3. Wetness Sensor (measures changes in electrical characteristics) 4. Present Weather System (detects rate of falling particles and temperature) |
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Define isoheyts |
Lines that connect equal rainfall. Can also show the least and most rainfall that occurred over time (interpolation- colour is used to show this) |
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Define isobars and isotherms |
Isobars: Lines that connect equal air pressure Isotherms: Lines that connect equal temperature |
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What do closer isobars represent? |
The closer the isobars, the stronger the wind speed |
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In what direction will circulation be in each hemisphere? |
Southern: Anti - clockwise around high pressure and clockwise around low pressure. REVERSED FOR NORTHERN |
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What does L and H indicate on weather maps? |
'L' indicates the lowest pressure in the cell and 'H' indicates the highest pressure in the cell |
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In which direction does wind travel? (regarding pressure) |
Wind ALWAYS travels from a high to low pressure area |
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Another name for a low pressure area |
Tropical cyclone |
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Provide three ways to measure air pressure |
1. Barometer- mecury in bowl with tube that moves according to pressure of gases 2. Aneroid barometer - metallic box in which sides expand with pressure differences 3. Barograph - measures pressure for a week by ink line with moving drum |
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Give properties of: 1. Low pressure areas 2. High pressure areas |
1. Low pressure: clouds and rainfall 2. High pressure: clear skies |
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How are weather satellites situated? |
They are geostatic (in fixed position) but rotates with the earth - 36000 km above |
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Give 4 other ways (apart from satellite) that gathers weather data |
1. weather balloons with transmitters 2. floating buoys 3. weather stations 4. ships and aeroplanes |
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How is weather data summarized? |
By a synoptic weather map that uses symbols to represent weather conditions |
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Define cold front |
A boundary between approaching cold and warm air in front of it. The direction of the cold air is indicated by the direction of triangles |
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Define warm front |
A boundary between approaching cold and warm air ahead of it. Direction of the warm air is indicated by the directions of the semicircles |
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How is wind direction indicated? |
From where the wind comes from! |
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What are station models? |
They are models that summarize the weather conditions for the day for a particular region |
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At what time are weather recordings made? |
At Greenwich meridian 12:00 |
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Define isobaric interval |
The difference in pressure between two consecutive isobars |
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How is a pressure cell recognized? |
By the isobars that form a closed circular shape |
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Give one way a high pressure cell is recognised |
It can be recognized by increasing hectoprascal readings toward middle of cell |
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Name four items of data satellites gather from the surface of the earth |
1. Rainfall 2. Wind Speed 3. Land surface temps 4. Frequency of frost, dew or snow |