Climatology – MID - LATITUDE CYCLONES
Mid-latitude cyclone = A low pressure cell which develops in the mid-latitudes and travels WEST to
EAST
Low pressure cell (cyclone)
Develops in mid-latitudes = between 35˚ and 70˚ north and south of the equator, along
POLAR FRONT
Polar front = the front where the cold polar air meets the warm subtropical air (front =
where two air masses of different temperatures meet)
Cold air wedges underneath the warm air causing it to rise and cool and condense = clouds
and rain
Travels West to East
Occur mainly over ocean and coastal areas
Brings COLD, wet, windy weather
Winds converge into the centre in a clockwise direction in the southern hemisphere and an
anticlockwise direction in the northern hemisphere
Cyclone = Clockwise
This is due to the CORIOLIS FORCE = The force which deflects wind to the LEFT in the
southern hemisphere and to the RIGHT in the northern hemisphere due to Earth’s rotation
on its axis. (Coriolis force is greatest at the poles and does not occur within 5˚ of the
equator)
Pressure is low at the centre and increases outwards (<1000 hPa)
Diameter = 1500-3000km and can travel 1200km in a day
MLC (mid-latitude cyclone) in South Africa:
Southern tip of SA = 37˚ south, therefore the cold front resulting from the MLC only reaches
SA in winter (This is why Western Cape = winter rainfall)
This is when all the pressure belts and wind systems move NORTH with the HEAT EQUATOR
Bands of high- or low-pressure surrounding earth at certain latitudes (e.g. Equatorial low- pressure
belt at the equator)
Conditions necessary for formation:
1. Air masses of different temperatures need to meet resulting in a front (POLAR FRONT)
2. The cold air mass wedges underneath the warm air mass resulting in a pressure gradient
3. A bend or disturbance needs to occur in the polar front (Jet streams = a band of very strong
westerly winds high up in the atmosphere which partly control the development of a MLC)
which causes the Isobars to form a more circular pattern
4. A low-pressure cell forms in the centre and winds are deflected and blow into the LP (low-
pressure)
Mid-latitude cyclone = A low pressure cell which develops in the mid-latitudes and travels WEST to
EAST
Low pressure cell (cyclone)
Develops in mid-latitudes = between 35˚ and 70˚ north and south of the equator, along
POLAR FRONT
Polar front = the front where the cold polar air meets the warm subtropical air (front =
where two air masses of different temperatures meet)
Cold air wedges underneath the warm air causing it to rise and cool and condense = clouds
and rain
Travels West to East
Occur mainly over ocean and coastal areas
Brings COLD, wet, windy weather
Winds converge into the centre in a clockwise direction in the southern hemisphere and an
anticlockwise direction in the northern hemisphere
Cyclone = Clockwise
This is due to the CORIOLIS FORCE = The force which deflects wind to the LEFT in the
southern hemisphere and to the RIGHT in the northern hemisphere due to Earth’s rotation
on its axis. (Coriolis force is greatest at the poles and does not occur within 5˚ of the
equator)
Pressure is low at the centre and increases outwards (<1000 hPa)
Diameter = 1500-3000km and can travel 1200km in a day
MLC (mid-latitude cyclone) in South Africa:
Southern tip of SA = 37˚ south, therefore the cold front resulting from the MLC only reaches
SA in winter (This is why Western Cape = winter rainfall)
This is when all the pressure belts and wind systems move NORTH with the HEAT EQUATOR
Bands of high- or low-pressure surrounding earth at certain latitudes (e.g. Equatorial low- pressure
belt at the equator)
Conditions necessary for formation:
1. Air masses of different temperatures need to meet resulting in a front (POLAR FRONT)
2. The cold air mass wedges underneath the warm air mass resulting in a pressure gradient
3. A bend or disturbance needs to occur in the polar front (Jet streams = a band of very strong
westerly winds high up in the atmosphere which partly control the development of a MLC)
which causes the Isobars to form a more circular pattern
4. A low-pressure cell forms in the centre and winds are deflected and blow into the LP (low-
pressure)
