Cloud Base Calculator

The first thing you can estimate with this cloud base calculator is the altitude at which clouds form. For that, you will need two measurements:

• Air temperature - The temperature of the air, as measured with a regular thermometer.
• Dew point - The temperature at which water condensates, measured at the same elevation above sea level as the air temperature. If you are unsure how to measure it, head to our dew point calculator for more details and quick conversion between humidity levels and dew point.

Apart from these two values, you should note down the elevation above sea level at which you took these measurements. By default, our cloud base calculator assumes this elevation is equal to 0.

Once you have determined all of these values, the cloud altitude will be calculated automatically according to the following formula:

cloud base = (temperature - dew point) / 4.4 × 1000 + elevation

In this formula, the temperature and dew point are expressed in degrees Fahrenheit, and the elevation and cloud base altitude are expressed in feet. If you want to use Celsius and meters, the equation looks like this:

cloud base = (temperature - dew point) / 10 × 1247 + elevation

Where does the formula come from? Let's analyze it in detail. Clouds are formed when water vapor condensates. This, in turn, happens when the air temperature is equal to the dew point, or - in other words - when the spread (difference) between these two values is equal to 0.

The rate at which air cools is estimated at 5.4°F per 1000 feet of altitude. The dew point decreases slower - at about 1.0°F per 1000 feet. That means that per 1000 feet, the spread decreases by 4.4°F. Converting this all into SI units, you get values of 0.984°C per 100 m, 0.182°C per 100 m, and 0.802°C per 100 m, respectively. We've converted this into 10°C per 1247 meters for simplicity in the equation above.

If you look at the formula above closely, you will notice that this is exactly how it works: you can use it to determine at what altitude the spread between the dew point and the temperature is equal to zero. At the end, you have to add the elevation of the measuring station to obtain the true altitude above sea level.

Now that you know the minimum altitude at which clouds can form, you can also calculate their temperature. Our cloud base calculator applies the following formula:

cloud temperature = temperature - 5.4 × (cloud base - elevation) / 1000

Again, all temperatures are expressed in degrees Fahrenheit and all elevations in feet.

How did we arrive at this formula? We already know that temperature decreases by 5.4°F per 1000 feet of altitude. That means that per every 1000 feet of difference between the cloud base altitude and the altitude of your measuring point, the air temperature will decrease by 5.4°F. In Celsius and meters, our formula looks like this:

cloud temperature = temperature - 0.984 × (cloud base - elevation) / 100

🔎 Want to learn more about weather, clouds, and rain? We have our rainfall calculator and even our rain to snow calculator waiting for you.