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Atmosphere (Weather (Cloud (Cumulonimbus (Thunderstorm - lightning and…
Atmosphere
Weather
Typhoon
Wind speed <62km/hr = tropical depression
Wind speed >63km/hr = tropical storm
Wind speed >119km/hr = tropical cyclone
Formation:
- Warm ocean temperature > 26.5oc - energy source & water vapor - latent heat release during condensation of wv
- 10-20 oN/S
- Coriolis Force to drive spinning motion - increase due to Conservation of Angular Momentum that rotating speed increases as air moves towards centre
- Air pressure > 950 hPa - rising air causes pressure decrease
Dissipation:
- Latent heat cut off when moves inland
- When large scale flow aloft is unfavorable, diminish intensity
Wind
Coriolis Force -
Acts on wind velocity
Modify wind direction
Deflection increases with increasing latitude
Deflection increases with increasing wind speed
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Cloud
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Cumulonimbus
Thunderstorm - lightning and thunder
1. warm, moist, unstable air
2. upward air movement
3. within ITCZ
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Front
Warm front - warm air mass moves over a colder air mass - gentle gradient 1:200, wide spread clouds with light to moderate precipitation
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Cold front - cold air mass pushes under a warm air mass, steep gradient 1:100, short heavy rain and thunderstorm
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Precipitation
Process
Bergeron process: most ppt originate from ice crystal in high attitude, WV attached to ice crystal, grow larger in size and fall
Collision-Coalescence: raindrop coalesces and form large rain droplets, due to high surface tension, droplets breaks and fall as several small droplets
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Air Pressure controlling
Water vapor
More WV, density lower, pressure lower.
Because molecular weight of H2O is less than N2 or O2
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Air movement
Convergence aloft = Divergence surface-wind = anticyclone
→ net inflow of sinking air, higher pressure
Divergence aloft = Convergence surface-wind = cyclone
→ net outflow of rising air, lower pressure
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Air circulation
Scale
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Macroscale
- Synopic (1000-5000km) days to weeks
- Plantery (5000-40000km) weeks to more
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Pressure cells
- Hadley
- Ferrel
- Polar
- Polar/ Subtropical Jet stream - help balance Earth's heat by bring warm air North and cold air South
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Pressure Belts
ITCZ - most solar radiation, most ppt, least pressure
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Thermal Structure
Mesosphere -
- coldest place of mesopause, very scarce wv can sublimate into polar nuctilucent clouds
- contains little ozone to absorb UV energy
- temperature decreases with height
Stratosphere -
- ozone layer with peak conc at 25 km
- weak vertical motion, free of clouds
- less UV energy penetrate deeper due to UV absorption by ozone near the top which cause heating
- temperature increases with height
Thermoshpere -
- contains little mass
- cloudness and no wv
- oxygen and nitrogen molecules absorb solar energy cause warming
- temperature increases with height
- air density is so low that very little heat is transferred, cannot feel heat
Troposphere -
- contains 80% of the air mass, wv
- strong vertical motion & weather take place
- surface heated by solar radiation
- temperature decreases with height
Air Temperature
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Adiabatic lapse rate - rate at which the air parcel of forced rising air cools adiabatically with height, meaning no addition or removal of heat or energy.
Wet adiabatic rate - above the condensation level, wv condenses, latent heat releases, slower cooling rate of the air.
Rate of cooling is less than dry adiabatic rate.
Dry adiabatic rate - below the condensation level, dry air lifted, temperature cools for every 1000m.
Factor affecting
- Latitude and seasons
- Land and Sea
- Altitude
- Cloud cover and Albedo
- Ocean current
- Windward and leeward coast
Air Stability
Stable - Air parcel colder than surrounding, it resists uplift, tends to return its original position
Unstable - Air parcel warmer than surrounding, it tends to rise
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Air Uplift
- Orthographic uplift - sir forced upwards over a hilly area
- Frontal wedging - warm less dense air forced up over a package of cold dense air
- Convergence of two air masses
- Localized Convective uplifting
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Weather Observing Tools:
- ASOS
- Radiosonde
- Doppler Weather Radar
- Satellite
Hydrosphere
Problem
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Over withdrawal - land subsidence, ground collapse
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Groundwater & WaterTable
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Perched Water Tables - GW lies above the regional water table. In lens shape permeable layers with impermeable layer at the bottom.
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Artesian well - under enough pressure, water rise above the surface level of the aquifer on its own
Cave formation
- Thick limestone bedrock - depth
- Significant rainfall - carbonic acid
- Water table below ground - dissolve bi-carbonate
- Temperature to tropic warmth - fasten dissolution process
Ocean
Ocean current
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La Nina
strengthen easterly trade wind, larger push the warm water to far western side, more cold water upwelling in the east. Thunderstorm further west
El nino
weaken easterly trade wind, less push for the warm water piling to the western side and to the central and the east, less cold water upwelling in the east.
Thunderstorm in central, west experiences descending air and drought
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Wind effect
Ekman's spiral & transport -
- Coriolis force deflect surface currents, increasing deflection with increasing depth
- decreasing speed with increasing depth
Equatorial upwelling
Trade Winds & Coriolis effect - pulls surface water away from the equatorial region, resulted in divergence, causing upwelling of deeper water to replace the surface water.