Earth science

Atmosphere and weather

Layers, wind, clouds, fronts.

Basics

Atmospheric layers

Troposphere: weather, temperature falls with height. Stratosphere: ozone, temperature rises. Mesosphere: falls again. Thermosphere: thin, hot. Weather lives in the troposphere.

Wind

The pressure-gradient force pushes air toward low pressure. Coriolis deflects to the right in the north, left in the south. Friction matters near the ground.

Fronts and clouds

Cold air undercutting: cold front (narrow, intense rain). Warm air overrunning: warm front (broad, lighter rain). Cumulus grows vertically; stratus spreads. Dew point is the saturation temperature.

Formulas

Hydrostatic balance

ΔP ≈ −ρ g Δz

Pressure falls with height. Basis of weather maps and altimeters.

Symbols

  • P pressure
  • z height

Dry adiabatic lapse rate

Γ_d ≈ 9.8 °C / km

Unsaturated rising air cools by expansion. The moist lapse rate is smaller.

Ideal gas (air)

P = ρ R_specific T

Links pressure, density, and temperature. At a given P, warmer air is less dense.

Symbols

  • R_specific specific gas constant for dry air

Key table

Tropopause mid-latitudes about 10–12 km
Composition N₂ ~78%, O₂ ~21%, Ar ~0.9%, CO₂ trace and rising

In this field