CLIMATE AND WEATHER
CHAPTER 1 : MID-LATITUDE CYCLONES
General Characteristics
Develops between 40° and 60° N&S
Low pressure cell ( Hot air rises - forms low pressure cell at surface )
Oceans and Coastal areas
Cold, wet and windy weather ( Steeper the gradient, stronger the
wind )
Winds converge
Diameter 1500 - 3000 km
Moves from East to West
Travels 1200 km per day
Lasts up to 5 days
Coriolis Force
Southern Hemisphere - Winds blow Clockwise
Northern Hemisphere - Winds blow Anti-clockwise
Formation
1. Polar front forms when warm air meets cold air
2. Warm air is pushed up polar cell and cold air wedges underneath
3. Pressure gradient formed
4. Westerly and easterly winds blow along gradient
5. Bend in front may form ( jet streams and mountains )
6. Isobars form a circular pattern and low-pressure cell
Stages of development
Initial Stage
Bend forms in polar front
Strong winds and Clouds
Mature Stage
Bend deepens and gradient becomes steeper
Cold front - Strong winds, overcast skies and rain
Warm front - Warmer weather and broken clouds
Occluded Stage
Cold sector gradually takes over warm sector
Cold with nimbus clouds and light rain
Degeneration Stage
, Ends a gust of air at ground level
Low pressure cell disappears and isobars even out
Cold with cloud and rain clears
Cold front conditions
1. Temperature decreases
2. Pressure increases
3. Humidity decreases
4. Cumulonimbus clouds
5. Wind now blows south ( Backing - Anticlockwise change in direction )
Warm front conditions
1. Temperature increases
2. Pressure decreases
3. Humidity increases
4. Cirrus and altostratus clouds from before nimbostratus clouds
Cold front occlusion
1. Air ahead of cold front is warmer than air behind front
2. As air rises, nimbostratus clouds form
3. Rain falls
Warm front occlusion
1. Air ahead of warm front is cooler than air behind front
2. As air rises, nimbostratus clouds form
3. Rain falls
Weather maps
CHAPTER 1 : MID-LATITUDE CYCLONES
General Characteristics
Develops between 40° and 60° N&S
Low pressure cell ( Hot air rises - forms low pressure cell at surface )
Oceans and Coastal areas
Cold, wet and windy weather ( Steeper the gradient, stronger the
wind )
Winds converge
Diameter 1500 - 3000 km
Moves from East to West
Travels 1200 km per day
Lasts up to 5 days
Coriolis Force
Southern Hemisphere - Winds blow Clockwise
Northern Hemisphere - Winds blow Anti-clockwise
Formation
1. Polar front forms when warm air meets cold air
2. Warm air is pushed up polar cell and cold air wedges underneath
3. Pressure gradient formed
4. Westerly and easterly winds blow along gradient
5. Bend in front may form ( jet streams and mountains )
6. Isobars form a circular pattern and low-pressure cell
Stages of development
Initial Stage
Bend forms in polar front
Strong winds and Clouds
Mature Stage
Bend deepens and gradient becomes steeper
Cold front - Strong winds, overcast skies and rain
Warm front - Warmer weather and broken clouds
Occluded Stage
Cold sector gradually takes over warm sector
Cold with nimbus clouds and light rain
Degeneration Stage
, Ends a gust of air at ground level
Low pressure cell disappears and isobars even out
Cold with cloud and rain clears
Cold front conditions
1. Temperature decreases
2. Pressure increases
3. Humidity decreases
4. Cumulonimbus clouds
5. Wind now blows south ( Backing - Anticlockwise change in direction )
Warm front conditions
1. Temperature increases
2. Pressure decreases
3. Humidity increases
4. Cirrus and altostratus clouds from before nimbostratus clouds
Cold front occlusion
1. Air ahead of cold front is warmer than air behind front
2. As air rises, nimbostratus clouds form
3. Rain falls
Warm front occlusion
1. Air ahead of warm front is cooler than air behind front
2. As air rises, nimbostratus clouds form
3. Rain falls
Weather maps
