Atmospheric Temperature Calculator
Calculation Results
At an altitude of meters:
Total Altitude Change: meters
Total Temperature Change: °C
What is the Normal Lapse Rate?
The Normal Lapse Rate refers to the average rate at which atmospheric temperature decreases with an increase in altitude within the troposphere. While actual atmospheric conditions vary based on humidity, wind, and time of day, the standard (or "normal") lapse rate is globally accepted for general calculations in aviation, meteorology, and mountaineering.
The standard value used for the normal lapse rate is:
- 6.5°C per 1,000 meters (approximately 3.5°F per 1,000 feet).
How the Calculation Works
This calculator determines the estimated air temperature at a specific target altitude based on a starting temperature and altitude. The formula uses a linear relationship between altitude and temperature decrease.
The formula used is:
Tfinal = Tbase – ( Lapse Rate × ( ( Htarget – Hbase ) / 1000 ) )
Where:
- Tfinal: The temperature at the target altitude.
- Tbase: The starting temperature (e.g., at sea level).
- Lapse Rate: The rate of cooling (Standard is 6.5°C/km).
- Htarget: The altitude where you want to know the temperature.
- Hbase: The starting altitude.
Example Calculation
Imagine you are at sea level (0 meters) where the temperature is 15°C. You are planning to hike to a peak at 2,000 meters. Using the normal lapse rate of 6.5°C/km:
- Altitude Change: 2,000m – 0m = 2,000m (or 2km).
- Temperature Drop: 2km × 6.5°C = 13°C.
- Final Temperature: 15°C – 13°C = 2°C.
At the peak, the estimated temperature would be 2°C.
Factors Influencing Lapse Rate
While the Normal Lapse Rate is a useful average, the Environmental Lapse Rate (ELR) fluctuates significantly in the real world due to:
- Moisture Content: Moist air cools more slowly than dry air. The saturated adiabatic lapse rate is often lower (around 5°C/km).
- Time of Day: Surface heating during the day can steepen the lapse rate near the ground.
- Temperature Inversions: Sometimes temperature actually increases with height (negative lapse rate), causing smog and fog to become trapped.
Applications of this Calculator
Understanding vertical temperature gradients is essential for:
- Pilots: Determining freezing levels and engine performance.
- Hikers & Mountaineers: Preparing gear for colder temperatures at summits.
- Engineers: Designing systems that operate at high altitudes.