HesapHanem

Adiabatic Lapse Rate Calculator

Enter surface temperature and altitude gain to find the cooled air temperature.

Result

10.30 °C
14.70 °C
9.8 °C/km

How it is calculated

The tool subtracts a fixed cooling rate times the altitude gain from the starting temperature: drop = rate × height and T = Tsurface − drop. Temperature is in °C, height is the altitude gain in metres, and the rate is in °C per metre. In dry mode the rate is 0.0098 (9.8 °C/km); in wet mode it is a single fixed value of 0.005 (5.0 °C/km). Real saturated air cools at a rate that varies with temperature and moisture, so wet mode is a rough middle value, not a full psychrometric calculation. The engine does not check for cloud formation: it applies the one chosen rate for the whole climb. A negative height is accepted and produces warming, as for a descending parcel.

Worked example

An air parcel starts at 25 °C at the surface and rises 1,500 m in dry mode. The rate is 9.8 °C/km, which is 0.0098 °C per metre. Drop = 0.0098 × 1,500 = 14.70 °C. New temperature = 25 − 14.70 = 10.30 °C. With wet mode instead, the rate would be 5.0 °C/km, the drop 7.50 °C, and the parcel would end at 17.50 °C, showing how much condensation heat slows the cooling.

Try this example →

Common mistakes

  • Typing the height in kilometres or feet. The input is metres, so 1.5 for 1,500 m would give a drop of only 0.01 °C.
  • Using wet mode for air that is not saturated. Clear, dry air follows the dry rate until it reaches its condensation level; only cloudy, saturated air cools more slowly.
  • Treating the result as the temperature at a mountain station. It is a parcel of air rising adiabatically, whereas the real ambient temperature profile (the environmental lapse rate) is often different.
  • Applying one rate across a climb that passes through the cloud base. The engine does not switch from dry to wet partway, so split such a climb into two calculations.

About this calculator

As an air parcel rises it expands and cools because atmospheric pressure drops with altitude — the rate of that cooling is the adiabatic lapse rate. Dry, unsaturated air cools at the dry adiabatic lapse rate (DALR) of about 9.8°C per kilometer; once the parcel is saturated and water vapor condenses, the released latent heat slows the cooling to the moist adiabatic lapse rate (MALR), which in nature varies from about 4 to 9°C per kilometer with temperature and moisture content. This calculator offers a dry mode (9.8°C/km) and a moist mode that uses a fixed 5.0°C/km, applied to your surface temperature and altitude gain to find the parcel's new temperature.

Meteorologists use lapse rates to judge atmospheric stability and forecast whether rising air will keep building into thunderstorms, pilots use the same physics to estimate density altitude and cloud base height, and mountaineers and hikers use it as a rule of thumb to predict how much colder it will be at altitude.

Was this helpful?

You can pick up to 3 reactions.

Comments (1)

  • Editorial team

    Mountain weather is a good use of two runs. Lift a 20 °C parcel 2,000 m in moist mode and it reaches 10.00 °C; then start from 10 °C and enter minus 2,000 m in dry mode, and it ends at 29.60 °C. That is a rough picture of a warm, dry lee slope. Which mountain or flight level are you trying to estimate?

Popular calculators

Loan Calculator

Monthly payment, total interest and full amortization schedule.

Percentage Calculator

Percent change, percent of, and ratio calculations.

Discount Calculator

Calculate final price, savings, and discount amount.

BMI Calculator

Body mass index from height and weight (metric or imperial).

Age Calculator

Compute your exact age in years, months and days from a birth date.

Compound Interest Calculator

Calculate the final amount and interest earned with compounding.

All Calculators