What's the altitude of the flat base of Cumulus clouds? Is there a formula that describes the altitude of clouds with respect to the local temperature? I think of the flat bases of Cumulus clouds.
Thanks...
 A: According to Ahrens R.

The bases of cumulus cloud can be estimated
  quite easily when the surface air temperature
  and dew point are known. If the air is not
  too windy, we can assume that entrainment of
  air will not change the characteristics of a rising
  thermal. Since the rising air cools at the dry
  adiabatic rate of about 10°C per 1000 m, and
  the dew point drops at about 2°C per 1000 m,
  the air temperature and dew point approach
  each other at the rate of 8°C for every 1000 m
  of rise. Rising surface air with an air temperature
  and dew point spread of 8°C would produce
  saturation and a cloud at an elevation of
  1000 m. Put another way, a 1°C difference between
  the surface air temperature and the dew
  point produces a cloud base at 125 m. Therefore,
  by finding the difference between surface
  air temperature (T) and dew point ($T_{d}$), and
  multiplying this value by 125, we can estimate
  the base of the convective cloud forming overhead,
  as
  $H_{meter}=  125 (T-T_{d})$ .

