The dew point corresponds to the value of the temperature at which the air becomes saturated with water.
This threshold is dependant on pressure, humidity and the surrounding temperature. If the temperature drops below the dew point, then the water condenses, forming dew. Depending on the wind speed, this water vapour may form dew, fog or low cloud.
This is a useful indicator when dealing with large crops at harvest time, for example. In fact, water condensation makes harvesting more difficult. Knowing the dew point can therefore help farmers determine the optimum windows of intervention and to manage their organisation. It also helps them adapt in real time.
The dew point is also a telling indicator for other crops (viticulture, arboriculture...). It is a useful way to keep an eye on the drop in temperature when the sun goes down. During periods of cold weather, the dew point allows users to anticipate the appearance of frost. The foliage of vines, for example, cools down more quickly than the air, and condensation can be seen forming on it. Often the air temperature is > 0°C, but the soil and the plants are already ‘white’ (in other words, it is a hoar frost and not a true air frost).