What is the dew point temperature?
If we know the surface temperature and the dew point temperature, we can make a simple calculation to determine the altitude at which the base of a convective cloud (cumulus) will be located. If the wind is not strong, we can assume that the air conditions will not change as we ascend vertically. Knowing that the dry adiabatic lapse rate is -10°C per 1,000 meters of ascent and that the dew point drops by 2°C per 1,000 meters, we see that both temperatures converge by 8°C per 1,000 meters. Looking at this another way, we see that for every 1°C difference between the surface temperature and the dew point, a cloud with a base at 125 meters is formed. In summary, we can estimate the base of a convective cloud using the following formula:
Base height of a convective cloud = 125 × (surface temperature – dew point temperature)
