Friday, September 23, 2005
GEOG - WEATHER STUDIES
Temperature: degree of heat or cold
Factors affecting temperature:
1. altitude: normal lapse rate 6.4oC per 1000m
2. latitude: angle of incidence
3. aspect: affects temperature regions
4. land surface: vegetation cooler than concrete
5. ocean currents: N Alantic drift warm oyashio cold
6. distance from sea: maritime/continental influence
7. humidity: high>more cloud cover
Instrument: Six’s thermometer
U bend – mercury
Upper limbs – alcohol
Right bulb with vacuum
Humidity: state of atmosphere(water vapour content)
Depends on temperature: warmer air holds more
Saturated: holds max amt at a particular temp
Relative humidity: percentage of amt it holds against total amt it can hold
Instrument: hygrometer (wet + dry bulb thermometer)
Wet: wrapped w muslin kept moist w distilled water
Wet bulb depression: more w less humidity
Stevenson screen hygrometer, six’s thermometer
painted white
more than 1m above ground
wooden
louvered sides
sited in open area with short grass
Rainfall
1. convectional: accompanied by lightning & thunder
-high humidity & temp, tropical areas, temperature regions in summer
-heat from ground warms up air which rises
-heavy rain, short period, falls in afternoon
2. relief: moist onshore air forced upwards
-windward & leeward sides
3. frontal: when 2 masses of air with different masses, temperatures and densities meet
a. cold front: cold air slips under warm air
-warm air forced upwards
-heavy rain, short period, small area
b. warm front: warm air rises gently
-gentle rain, long period, wide area
Instrument: rain gauge: outer & inner copper casing, glass bottle, funnel with tapering end
1. open area: rain can enter from any angle, prevent dripping, blockage of opening by leaves
2. sunk into grassy ground (one third below ground): cooler, prevent toppling & splashing
_read evry 12h in mm, poured in measuring cylinder
_small opening to minimise evaporation
Anemometer: 3 or 4 cups joined to the ends of metal rods fixed to a spindle
-sited 10m above ground in open area
Wind vane: freely moving pointer on a vertical shaft
-shows direction which the wind is blowing from
-sited 10m above ground away from obstruction
Air pressure: air pressure higher nearer ground & decreases with height
warm air expands, rises,results in low pressure below
cold air sinks, exerts high pressure below it
Instrument: barometer (aneroid)
Metal box that is a partial vacuum, flexible corrugated top that moves according to change in pressure. The pressure is read off a calibrated dial
Planetary pressure system
1. doldrums(equatorial low pressure belt) 5oN to 5oS
-caused by high temperatures (warmed air rises)
2. sub-tropical high (horse latitudes) 30oN and 30oS
-air frm doldrums move up and cools, sinks
3. sub-polar low pressure belts 60oN and 60oS
-polar & sub-tropical winds converge, forced to rise
4. polar high pressure belts 90oN and 90oS
-due to low temperatures (cooled air sinks)
Planetary wind system Coriolis effect: deflection
Winds move frm high pressure to low pressure areas
-deflected to right in northern hemisphere
-deflected to left in southern hemisphere
1. trade winds: blow from sub-tropical to doldrums
North hemi: deflected to right, north-east trades
South hemi: deflected to left, south-east trades
intertropical convergence zone: converge at equator
2. westerlies: blow frm sub tropical to sub polar
North hemi: deflected to right, south westerlies
South hemi: deflected to left, north westerlies
3. easterlies: blow frm polar to sub polar
North hemi: deflected to right, north easterlies
South hemi: deflected to left, south easterlies
Sea and land breezes: small scale local winds
-due to diff rates of heating up and cooling down
Day: land hotter, lower pressure, sea breeze to land
Ngt: land cooler, higher pressure, land breeze to sea
Monsoons: large scale seasonal winds
-due to diff rates of the large land masses
End & beginning of yr: sun overhead near tropic of Capricorn; north hemi have winter, south hemi have summer; winds arrive in north china & japan as north west monsoon and as north east monsoon in south china n SEA; wind deflected to left in south hemi, arrive in australia & indonesia as north west monsoon
Middle of yr: sun overhead near tropic of cancer; north hemi have summer, south hemi have winter; wind deflected to right in north hemi, arrives in SEA as south west monsoon, south east monsoon in japan & north china, south west in india
yay! undetailedness :))) - lala
Factors affecting temperature:
1. altitude: normal lapse rate 6.4oC per 1000m
2. latitude: angle of incidence
3. aspect: affects temperature regions
4. land surface: vegetation cooler than concrete
5. ocean currents: N Alantic drift warm oyashio cold
6. distance from sea: maritime/continental influence
7. humidity: high>more cloud cover
Instrument: Six’s thermometer
U bend – mercury
Upper limbs – alcohol
Right bulb with vacuum
Humidity: state of atmosphere(water vapour content)
Depends on temperature: warmer air holds more
Saturated: holds max amt at a particular temp
Relative humidity: percentage of amt it holds against total amt it can hold
Instrument: hygrometer (wet + dry bulb thermometer)
Wet: wrapped w muslin kept moist w distilled water
Wet bulb depression: more w less humidity
Stevenson screen hygrometer, six’s thermometer
painted white
more than 1m above ground
wooden
louvered sides
sited in open area with short grass
Rainfall
1. convectional: accompanied by lightning & thunder
-high humidity & temp, tropical areas, temperature regions in summer
-heat from ground warms up air which rises
-heavy rain, short period, falls in afternoon
2. relief: moist onshore air forced upwards
-windward & leeward sides
3. frontal: when 2 masses of air with different masses, temperatures and densities meet
a. cold front: cold air slips under warm air
-warm air forced upwards
-heavy rain, short period, small area
b. warm front: warm air rises gently
-gentle rain, long period, wide area
Instrument: rain gauge: outer & inner copper casing, glass bottle, funnel with tapering end
1. open area: rain can enter from any angle, prevent dripping, blockage of opening by leaves
2. sunk into grassy ground (one third below ground): cooler, prevent toppling & splashing
_read evry 12h in mm, poured in measuring cylinder
_small opening to minimise evaporation
Anemometer: 3 or 4 cups joined to the ends of metal rods fixed to a spindle
-sited 10m above ground in open area
Wind vane: freely moving pointer on a vertical shaft
-shows direction which the wind is blowing from
-sited 10m above ground away from obstruction
Air pressure: air pressure higher nearer ground & decreases with height
warm air expands, rises,results in low pressure below
cold air sinks, exerts high pressure below it
Instrument: barometer (aneroid)
Metal box that is a partial vacuum, flexible corrugated top that moves according to change in pressure. The pressure is read off a calibrated dial
Planetary pressure system
1. doldrums(equatorial low pressure belt) 5oN to 5oS
-caused by high temperatures (warmed air rises)
2. sub-tropical high (horse latitudes) 30oN and 30oS
-air frm doldrums move up and cools, sinks
3. sub-polar low pressure belts 60oN and 60oS
-polar & sub-tropical winds converge, forced to rise
4. polar high pressure belts 90oN and 90oS
-due to low temperatures (cooled air sinks)
Planetary wind system Coriolis effect: deflection
Winds move frm high pressure to low pressure areas
-deflected to right in northern hemisphere
-deflected to left in southern hemisphere
1. trade winds: blow from sub-tropical to doldrums
North hemi: deflected to right, north-east trades
South hemi: deflected to left, south-east trades
intertropical convergence zone: converge at equator
2. westerlies: blow frm sub tropical to sub polar
North hemi: deflected to right, south westerlies
South hemi: deflected to left, north westerlies
3. easterlies: blow frm polar to sub polar
North hemi: deflected to right, north easterlies
South hemi: deflected to left, south easterlies
Sea and land breezes: small scale local winds
-due to diff rates of heating up and cooling down
Day: land hotter, lower pressure, sea breeze to land
Ngt: land cooler, higher pressure, land breeze to sea
Monsoons: large scale seasonal winds
-due to diff rates of the large land masses
End & beginning of yr: sun overhead near tropic of Capricorn; north hemi have winter, south hemi have summer; winds arrive in north china & japan as north west monsoon and as north east monsoon in south china n SEA; wind deflected to left in south hemi, arrive in australia & indonesia as north west monsoon
Middle of yr: sun overhead near tropic of cancer; north hemi have summer, south hemi have winter; wind deflected to right in north hemi, arrives in SEA as south west monsoon, south east monsoon in japan & north china, south west in india
yay! undetailedness :))) - lala
# we mugged! @ 9:33 PM 
