What is the approximate base of cumulus clouds when the temperature at 2,000 feet MSL is 10°C and the dewpoint is 1°C?

To determine the approximate base of cumulus clouds given the temperature and dewpoint, one must refer to the concept of the cloud base calculation. Cumulus clouds typically form when the air rises and cools to its dewpoint, leading to condensation.

In this scenario, we start with a temperature of 10°C at 2,000 feet MSL and a dewpoint of 1°C. The rule of thumb for estimating cloud base is to consider the temperature lapse rate, which is about 2°C per 1,000 feet.

First, we calculate the difference between the temperature and dewpoint: 10°C - 1°C = 9°C. To find the altitude where the air cools to the dewpoint level by considering the lapse rate, we can use the 2°C drop for every 1,000 feet:

• For each 2°C, it drops 1,000 feet.

• Therefore, for 9°C, the calculation is approximately (9°C / 2°C) * 1,000 feet = 4,500 feet.

Now, we add the starting altitude of 2,000 feet to the altitude calculated from the temperature drop:

2,000 feet + 4,500