Meteorology
Tropopause/Troposphere
• Troposphere
- Concerns aviators
• Tropopause
- Mid-latitudes ISA: 11km & -56.5°C
- Equator: 16km & -75°C
- Tropical (area around equator) tropopause 54000ft
- Separates troposphere with stratosphere
- Lower in summer, higher in winter
- Temp higher at poles
- Temp lapse rate changes abruptly
- Breaks: Core of jetstreams found here
- Area where temp change does not exceed 2/3 of 1°C/1000ft in altitude range of 6000ft
- Higher temperature of airmass = higher pressure & higher tropopause
• Stratosphere
- Ozone contained
- Layer absolutely stable
- Lower part temperature constant
• Stratopause
- 50km
• Determining Tropopause height with formula: 16km (winter) or 18km (Summer) x cos latitude
Temperature
• Insolation(Downward):
- Earth heating from heat energy from the sun, partly absorbed by atmosphere, partly reflected by clouds
mostly reaches surface
- Insolation max at noon
- Amount of heat depends on sun’s elevation & duration of insolation.
- Most significant warming is through convection(upward currents of air bringing heat) & condensation(release
of latent heat) of air
- Variation of solar energy at earth’s surface is the primary cause of weather
• Terrestrial radiation(Upward):
- Heat energy from the earth radiates to space/atmosphere/troposphere
- The clouds blocks radiation from slipping to space(from surface) i.e. clear nights = colder
- The main methods of heat transfer are through formation of clouds & outgoing long wave radiation.
• Inversion:
- Subsidence inversion is caused by an old pressure system.
- A valley inversion happens when cool dense air descends down valley slopes into basin.
- Main cause of terrestrial radiation is a cloud-free night in winter when the ground is dry. In winter, the ground
is colder than in summer, conduction cools the air above.
- Found commonly in stratosphere
• Diurnal variation:
- Highest temperature 2 hours after noon, lowest temperature half hour after sunrise.
- Highest diurnal variations: Deserts. Hot during day, cold at night.
- Lowest diurnal variations: Tropical areas.
- Variation is highest when sky clear & winds are weak.
- Variation bigger over larger land masses compared to the sea/other regions
- Wind increases difference in temperature between surface and 4ft (Mixing)
• Specific heat capacity:
- Amount of heat per unit mass required to raise the temperature by 1°C, i.e. higher specific heat = takes more time
to heat up
- Water has higher specific heat than land
- Grass less SH than concrete
- Rocks very low SH
• Isotherms: Tropical = 16000ft, Temperate = 6000ft, Polar = 0ft
