How this calculator works
The lower-atmosphere reference profile cools linearly to the tropopause at 11 km, then holds temperature constant to 20 km. Changing sea-level temperature shifts this whole illustrative profile. Height is geopotential altitude. This is a reference atmosphere, not a forecast: inversions, terrain, fronts and humidity alter observed lapse rates. The chart labels its chosen temperature and height units in the accompanying readout.
Formula
T(h) = T0 - 0.0065 min(h,11000) in kelvins, h in metres; valid here from -2000 to 20000 m.
Worked example
With 15 C at sea level, the model gives 8.5 C at 1000 m and -56.5 C at 11000 m. It remains -56.5 C through 20000 m.
Advertisement
Frequently asked questions
Does the temperature always decrease with altitude?
No. Real temperature inversions occur. This calculator shows an assumed standard-style profile.
Is this the dry adiabatic lapse rate?
No. The environmental reference lapse is 6.5 K/km; an unsaturated rising parcel cools at roughly 9.8 K/km.
What happens above 20 km?
Other standard-atmosphere layers apply. This page deliberately ends at 20 km.