Topic 2: Climate and Weather
Unit 1: Mid-latitude Cyclones
Mid-latitude cyclones: a cell of low pressure, containing a warm front and a cold front, which
brings rain in the winter to the Western Cape.
- Temperate cyclones
- Extra-tropical cyclones
- Temperate depressions
- Frontal depressions
General Characteristics
- Speed of movement from west to east: 30-50km/hr.
- Life span: 4-14 days
- Pressure: extensive low-pressure center
- Diameter of whole system: up to 3 000km
- Pattern of isobars: oval shaped
- Pressure gradient: not normally steep
- Contains a warm front and a cold front
- Occur in families: the cold front of an older depression is joined to the warm front of a
younger depression
The Effect of Pressure and Wind Patterns on Mid-Latitude Cyclones:
Mid-latitude cyclone in the Southern Hemisphere:
Winds blow around and into the low-pressure cell in a
clockwise direction. Wind is deflected due to Coriolis force
(force that causes the deflection of moving objects due to the
rotation of Earth on its axis)
Mid-latitude cyclone in the Northern Hemisphere:
Wind blows around and into the low-pressure cell in an
anticlockwise direction, also because of the Coriolis effect
Unit 1: Mid-latitude Cyclones
Mid-latitude cyclones: a cell of low pressure, containing a warm front and a cold front, which
brings rain in the winter to the Western Cape.
- Temperate cyclones
- Extra-tropical cyclones
- Temperate depressions
- Frontal depressions
General Characteristics
- Speed of movement from west to east: 30-50km/hr.
- Life span: 4-14 days
- Pressure: extensive low-pressure center
- Diameter of whole system: up to 3 000km
- Pattern of isobars: oval shaped
- Pressure gradient: not normally steep
- Contains a warm front and a cold front
- Occur in families: the cold front of an older depression is joined to the warm front of a
younger depression
The Effect of Pressure and Wind Patterns on Mid-Latitude Cyclones:
Mid-latitude cyclone in the Southern Hemisphere:
Winds blow around and into the low-pressure cell in a
clockwise direction. Wind is deflected due to Coriolis force
(force that causes the deflection of moving objects due to the
rotation of Earth on its axis)
Mid-latitude cyclone in the Northern Hemisphere:
Wind blows around and into the low-pressure cell in an
anticlockwise direction, also because of the Coriolis effect
