3. Surface condensation. Dew point

Let's consider the following scenario: 1 m ³ of air, unsaturated with water vapor, contained in a tightly sealed glass cube. Its temperature is gradually lowered. At a certain temperature, water droplets appear on the inner surface of the glass.

This physical phenomenon is explained by the fact that, when the temperature of the unsaturated air volume is lowered, the saturation limit for this air decreases, i.e. its relative humidity "increases". Thus, for a given temperature, RH ≥ 100%.

If the temperature is lowered further, part of the water vapour changes to liquid form: this marks the start of the surface condensation phenomenon.

The temperature at which the first signs of condensation appear is called the "dew point temperature" or "dew point". Note: T ≥T _...