Cloud Base Height Calculator
The cloud base is the altitude at which rising, cooling air reaches saturation and condenses into the flat bottom of a cumulus cloud. Pilots, glider and paraglider enthusiasts, and weather watchers all care about it because it marks the ceiling of comfortable flight and the start of thermals. This calculator uses the classic Espy estimate, which says the convective cloud base sits roughly at the height where the spread between the surface temperature and the dew point closes at a rate of about 2.5 degrees Celsius per one thousand feet. Enter the surface air temperature and the dew point, choose Celsius or Fahrenheit, and read the estimated cloud base above ground level in both feet and meters. It is a rule of thumb for fair weather cumulus, not a substitute for a proper sounding. All computation runs locally in your browser for immediate, private results.
How to use Cloud Base Height Calculator
- Enter the surface temperature.
- Enter the surface dew point.
- Read the estimated cumulus cloud base height.
- Use it as a rough ceiling estimate.
Frequently asked questions
How does it estimate cloud base height?
It uses the Espy formula, which multiplies the spread between surface temperature and dew point by about 125 meters per degree Celsius to estimate the lifting condensation level.
Why does a smaller temperature dew point spread mean lower clouds?
A small spread means the air is close to saturation, so it needs little lifting to condense, which puts the cumulus cloud base lower.
Is this an exact ceiling for aviation?
No, it is an estimate for fair weather cumulus bases; official ceilings depend on measured conditions, so use it as a planning guide rather than a precise value.
What is Cloud Base Height Calculator?
The cloud base is the altitude at which rising, cooling air reaches saturation and condenses into the flat bottom of a cumulus cloud. Pilots, glider and paraglider enthusiasts, and weather watchers all care about it because it marks the ceiling of comfortable flight and the start of thermals.
Is Cloud Base Height Calculator free to use?
Yes. Cloud Base Height Calculator is completely free, with no sign-up and no usage limits.
Does Cloud Base Height Calculator work in a web browser?
Yes. Cloud Base Height Calculator runs in any modern web browser. There is nothing to download or install.
Is my data private with Cloud Base Height Calculator?
Yes. Cloud Base Height Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.
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