Geography notes
Midlatitude cyclones
Cyclones are areas of low pressure.
In the southern hemisphere winds rotate clockwise
In the northern hemisphere winds rotate anticlockwise
Symbol for tropical cyclone =
Symbol for mid-lat cyclone =
Def: A low pressure cell which develops in the mid latitudes of 30* - 60* N/S of the equator
Characteristics of mid latitude cyclones
1. Travels west to east (westerly winds)
2. Also referred to as temperate cyclones, extratropical cyclones or depressions
3. Low pressure areas that extend over a area of 1500 - 3000 km
4. Gentle gradient = winds are not severe
5. Sectors of warm moist air and cooler dry air which are separated by fronts
6. Moves 1200 km a day
7. Weather will last 5 days
8. May occur in families of 3 or 4 systems
9. May migrate north or south according to the seasonal shift of the ITCZ ( inter
tropical convergence zone)
Conditions necessary for the formation of a mid latitude cyclone
1. At 50* N/S the equator warm air meets cool air
2. These air masses do not mix and are separated by the polar front ( Transition zone)
3. Disturbance will occur along the polar front to cause LP to form = winds to circulate =
mid-lat cyclone.
Stages of development of the mid latitude cyclone.
1. Initial stage
- A disturbance in the front may occur as result of:
1. Frictional drag ( winds travel in the opp direction)
2. Disturbance in the westernly belt
3. Winds moving over sea or land
4. Contrast of sea and land temperatures
Midlatitude cyclones
Cyclones are areas of low pressure.
In the southern hemisphere winds rotate clockwise
In the northern hemisphere winds rotate anticlockwise
Symbol for tropical cyclone =
Symbol for mid-lat cyclone =
Def: A low pressure cell which develops in the mid latitudes of 30* - 60* N/S of the equator
Characteristics of mid latitude cyclones
1. Travels west to east (westerly winds)
2. Also referred to as temperate cyclones, extratropical cyclones or depressions
3. Low pressure areas that extend over a area of 1500 - 3000 km
4. Gentle gradient = winds are not severe
5. Sectors of warm moist air and cooler dry air which are separated by fronts
6. Moves 1200 km a day
7. Weather will last 5 days
8. May occur in families of 3 or 4 systems
9. May migrate north or south according to the seasonal shift of the ITCZ ( inter
tropical convergence zone)
Conditions necessary for the formation of a mid latitude cyclone
1. At 50* N/S the equator warm air meets cool air
2. These air masses do not mix and are separated by the polar front ( Transition zone)
3. Disturbance will occur along the polar front to cause LP to form = winds to circulate =
mid-lat cyclone.
Stages of development of the mid latitude cyclone.
1. Initial stage
- A disturbance in the front may occur as result of:
1. Frictional drag ( winds travel in the opp direction)
2. Disturbance in the westernly belt
3. Winds moving over sea or land
4. Contrast of sea and land temperatures
