Mid-latitude Cyclones Flashcards
What are mid-cyclones?
Traveling low-pressure system
What are the sometimes called?
Depressions
Occur between?
40° to 60° N and S
Affect South Africa when?
Winter: pressure belts move northwards
Direction of mid-latitudes
From west to east
Necessary conditions for formation
Two different air masses converging: diff. temp. and moisture content
Friction: disturbed when flowing over uneven surfaces eg. Mountain ranges
Front: zone forms barriers between 2 diff. masses. Prevents mixing of air
Warm front conditions
Warm air glides over cool air = cirrus, stratus and nimbostratus (soft rain) clouds.
Warm sector
Rising warm air, moist air mass forms stratus clouds resulting in widespread,light rain
Cold front
Dense, cold air ridges underneath the warm sector and lifts it
Warm air rises,cools and condenses = cumulonimbus cloud.
Heavy rain and thunderstorms
Drop in temp
Pressure rises
Wind changes direction from nw to sw (backing wind)
Cold sector
Humidity decreases
Low temperatures
Possible snow in low lying areas
Hard rain short period of time
Impact of weather with mid-latitude cyclone
Rain in WP in winter
Brings cold snaps to plateau
Rough seas for fisherman
Heavy rainfall = flooding
Very cold temps can cause farmers to lose livestock
Snow on Drakensberg can cause damaged to crops and loss of stock
Water table rises in winter and periodic rivers flow.
Reasons for changes at the cold front
Temp drop
Wind ‘backs’ (sw)
Cloud cover increases
Clouds become cumulonimbus
Pressure drops, then rises
Heavy rainfall occurs over a small area
