Temperature at Altitude Calculator

How it works

T = T₀ − Γ × (h − h₀) · Γ = lapse rate: 6.5 °C/km standard atmosphere (ICAO), 9.8 °C/km dry adiabatic (g ÷ c_p), ≈ 5 °C/km saturated (varies 4–7 °C/km) · freezing level = h₀ + T₀ ÷ Γ

Air cools as it rises because pressure falls and the air expands. On average the troposphere cools by 6.5 °C per kilometre — the standard-atmosphere lapse rate used in aviation. Rising dry air cools faster, at the dry adiabatic rate of 9.8 °C/km, while saturated air inside clouds cools more slowly because condensation releases latent heat. Real days vary: temperature inversions (warmer air above) are common at night and in valleys, so treat the result as an estimate, valid up to about 11 km.

Worked example

It is 20 °C at sea level and you want the temperature at 3,000 m with the standard lapse rate: T = 20 − 6.5 × 3 = 0.5 °C, a drop of 19.5 °C. The freezing level is at 20 ÷ 6.5 × 1000 ≈ 3,077 m, just above the target altitude.

Sources: NOAA/NASA/USAF — U.S. Standard Atmosphere, 1976 · American Meteorological Society Glossary — Lapse rate

Frequently asked questions