Cloud Base Calculator (2024)

Say it's a beautiful summer day, and in the distance, you see some slow, puffy clouds lazily moving against the blue sky. Those are stratocumulus, and you can expect some rain later.

But... what is a cloud? Clouds are suspensions (aerosols) of water vapor, ice crystals, and other materials which become visible and confined in a particular region of the sky. We can find clouds on Earth and many other planets and moons with an atmosphere (though their composition changes with it: Titan has methane clouds, for example).

Clouds form when an air parcel containing water vapor moves upward, reaching a point where the vapor condensate around small nucleation points. The tiny droplets are now a cloud.

Though ethereal and seemingly random, clouds follow rigid physical rules, particularly for their formation parameters. It's time to learn what is the cloud base. The cloud base is the lowest possible altitude at which a cloud can form in a given layer and region of the atmosphere. We will see the formula for the cloud base calculations in a moment.

The cloud base is what we see when the clouds are right above us: it may change in appearance from white to very dark gray depending on the cloud thickness (the thicker, the more sunlight is scattered in, the higher layers).

For every point on Earth's surface, we can calculate the corresponding cloud base where — theoretically — the formation of a cloud becomes possible.

The cloud base formula requires you to know:

• The altitude of your station above sea level;
• The temperature at your station; and
• The dew point (if you need a refresh, visit our dew point calculator and our relative humidity calculator).

To calculate the dew point:

• Measure the spread (the difference) between temperature and dew point at your altitude;
• If you are calculating the height of the cloud base in Farhenheit, divide by $4.4$4.4 and multiply by $1,000$1,000;
• If you are calculating the cloud base in Celsius, divide the difference by $10$10 and multiply by $1,000$1,000.
• The result is the height of the cloud base relative to your elevation. Add your height above sea level to obtain the height of the cloud base relative to the sea level.

Let's put in number the formula for the cloud base height. If we are calculating the height of the cloud base starting in Farhenheit, we use this equation:

Where:

• $T$T — The temperature at the station;
• $T_{\text{D}}$TD​ — The dew point temperature;
• $h_{\text{base}}$hbase​ — The height of the cloud base; and
• $h_{\text{ele}}$hele​ — The elevation of the station.

Clouds happen when the temperature and the dew point's temperature are the same. When this condition is satisfied, the water in the air can condensate. Starting from ground level, the two temperatures change according to two specific "rules":

• The temperature decreases by $5.4\ \degree\text{F}$5.4°F every $100\ \text{ft}$100ft of altitude ($0.984\ \degree\text{C}$0.984°C every $100\ \text{m}$100m);
• The dew point temperature changes a bit slowlier, with $1\ \degree\text{F}$1°F or $0.182\ \degree\text{C}$0.182°C in the same height intervals.

The spread reduces accordingly, with a rate of $4.4\ \degree\text{F}$4.4°F per $100\ \text{ft}$100ft or $0.802\ \degree\text{C}$0.802°C per $100\ \text{m}$100m. When the spread is $0$0, we can find the bottom of our cloud.

🙋 Are you still interested in the science of our atmosphere? Visit our lightning distance calculator or our temperature at altitude calculator for other interesting facts and maths about the matter!