All you need to calculate an estimate for cloud height is the surface temperature and dew point temperature in degrees °C.
Here’s how to calculate a cloud base:
- Find the difference between the temperature at the surface and the dew point.
- Divide the difference between 2.5.
- Multiply the result by 1,000.
- This will then give you the height above ground level.
- Add the elevation of the airfield and this will give height above sea level.
Put in shorthand:
(Temp. – Dew Point) ÷ 2.5 X 1,000
A general rule of thumb is that the wider the gap between the temperature and dew point, the higher the cloud base is likely to be.
Obviously, there are many other factors which impact whether or not there will be cloud, how thick it will be, type and how much of the sky it will cover.
This method is most effective and accurate for convective cloud such as Cumulus, towering Cumulus and Cumulonimbus.
Another method to calculate cloud height is using the following:
(Air temperature at surface – dew point temperature) x 400
But, like most tools, estimations and forecasts, it’s always best to cross-reference with several models and tools to get a stronger overview of the expected weather.
For calculating non-convective cloud we recommend using Skew-T graphs or Aerological diagrams.