Ch 20 - Climatology Flashcards
The ITCZ
Where the NE and the SE trade winds converge
Sumer NH - 20-25’N (up to 28’ in Asia/china)
Avg. Lattitude in the Atlantic - 5’ N for the whole year
Most southerly position Jan - 20’S in Australia
Most northerly position in Jan - 5-7’N Dakar
Jan Global Pressure Systems
NH: Siberian High Canadian High Icelandic Low Azores High
SH: South American Low African Low Australian Low Ocean Highs
July Global Pressure Systems
NH: Icelandic Low; Greenland, Iceland, Baltic Canadian Low Asian/Baluchistan Low (Siberian) Azores High
SH:
The Southern Hemisphere High
Monsoon Climate
Is is both the summer and winder when the winds change direction.
Later version of land and sea breezes that change yearly, not diurnally.
July Monsoons
The ITCZ is north so the SE trade winds move north and turn into the SW Trade winds which pick up lots of water from the oceans and produce wet monsoons (July Monsoons) over; Africa, India, Asia where the trade winds converge
They bring with them TS, Downpours, Floods and CBs
January Monsoons
The ITCZ moves south over S. Africa and Northern Aus.. The NE trade winds want to get to the ITCZ so cross the EQ and turn into NW trade winds which converge with the SE winds over South Africa and Northern Australia bringing with them +RA, CBs, TS, Downpours, Flooding
Also brings with it cold dry air over india, Asia and North Africa from the cold Siberian high
Transition between the SW and the NE monsoons happens over; Sept., Oct. and Nov in the NH
El Niño
Warmer pacific sea temperature which decreases the density over the sea, reducing the trade wind speed and moves the warmer water back towards South America. South America then experiences TS with CBs and possible flooding whilst Australia experiences Droughts.
It effects the whole worlds climate
La Niña
Decreases the Pacific Temperature which causes the density above the sea to increase which increases the TW speeds. This moves the warm water over towards AUS and brings with it; CBs, TSs, Floods whilst S. America then experiences droughts
Zero Degree (0C) Isotherm
Is thee freezing level
Jan:
EQ - 16,000ft
40’N/S - 10,000ft
60’N/S - Surface
July:
EQ - 18,000ft
40’N/S - 16,000ft
60’N/S - 8000ft
Polar Outbreaks and Cold Air Pools
Only happen in winter in the N+S hemisphere
Cold air pushing very south (NH), eventually reaches critical mass and splits off becoming an isolated cold air pool in a hot air mass.
Slow moving cold, low pressure system
Between 10,000ft and 30,000ft
Can only be seen on upper charts 500-300hPa, never on surface.
2000km in diameter
Speed + direction is difficult to forecast
Can last for several days
Can move above Africa, resting on a high pressure air mass, creates great instability and can lead to snow in the Sahara
Examples of Cold Pools
Pampers from Antarctic to South America
South Africa called the south westerlies
Australia called the southerly busters or chilly-willies
Koeppen Global Climates
5:
Equatorial Wet Zones/Tropical Rain Climate
Arid Zone / Dry Climate
Temperate Zone
Snow Zones / Sub Arctic Climate
Polar Zone / Cold Desert
*Based on the amount of precipitation and vegetation at each (vegetation density)
Equatorial Zone - Tropical Rain Forest Region
Lat: 0-10’N/S
Temp; max 30/35C min 20/25C lowest diurnal and annual variations
Wx; Rain everyday Highest annual Rain No dry season
Other Info; Can experience equatorial double rains, 2 rainy seasons, September and march that tie in with the equinoxes (when the ITCZ is overhead)
Countries: Amazon, Borneo, Congo, Singapore
Equatorial Zone: Tropical Savannah Climate
Lat: 10-20’N/S
Temp; Lowest diurnal and annual variation >18C
Wx; Only 1 wet season in summer (ITCZ overhead)
Influenced by; High Pressure System
Countries; N. AUS, S. Brazil, Sudan, Ethiopia
Arid Zone: Desert
Lat; 20-35’N/S
Temp; Highest diurnal variations
Wx; No cloud, no winds - High pressure
Influenced by; sub-tropical belts of high pressure
Countries; Sahara, Gobi, Aus. Outback, Arabia, Arizona
