Types of frost

Not all types of frost occur for the same reason. Frost can occur in the air (understood as a mixture of gases) or from the earth's surface.

First of all, we must stress one concept. In physics, there is no such thing as cold. In its place is the concept of heat. When matter absorbs heat it increases its temperature, among other physical variables, and when it loses heat it cools down. A body can lose heat up to 0º Kelvin, which corresponds to -273º Celsius.

Not all frosts are the same. Nor are they equally dangerous. And most importantly, there is no such thing as cold, there is only heat radiation and heat absorption.

• Frost due to thermal inversion or terrestrial radiation.

These frosts are frequent on clear nights. The ground loses heat in the form of radiation and as there are no clouds to allow a greenhouse effect, the heat escapes from the earth. The result of this type of frost is that the ground surface freezes. It is called inversion frost, why the temperature normally decreases with altitude. When this type of frost occurs, the temperature increases with altitude. It is reversed. As we explained in the  Dew temperature cold air holds less water than warm air, so the water dissolved in the air in this type of frost condenses on the surface and freezes at high speed.

• Advection frost.

This type of frost usually lasts longer than one night. It occurs when air masses with a very high column below 0°C but at low altitude move into an area. These frosts, when prolonged, can cause severe damage to crops. Within this group of frosts are the white and black frosts.

It is problematic in a frost that is prolonged in time or occurs in situations of low humidity.

• White Frost

The dew temperature is also important in these frosts. If the freezing temperature is higher than the dew temperature, we have a white frost. The surface is frosted with a layer of white ice crystals. This type of frost is very interesting, as it is a very common case of "sublimation". Sublimation is when a matter, in this case water, goes from vapour to solid without passing through the intermediate state. This frost is not too damaging as the solid solid water on the crop prevents further heat from escaping from the crop. It insulates it. However, in this state the crop is very fragile to the touch. It is best not to touch them.

• Black Frost

The opposite of the previous case. When a frost occurs in conditions of low humidity, we are dealing with a black frost. It is so called because this is the colour that the crops take on after the frost. The tissues of the affected plants become necrotic and die, taking on a brown or blackish colour. If there had been humidity, a lot of these tissues could be saved. Some crops have a frost protection technique. This involves watering at the time of the frost so that the liquid water protects the crop.

Water gives off heat during freezing, and once frozen it acts as a heat insulator.

Frosts are dangerous, but they can be combated with various techniques such as forced ventilation, irrigation, or even for high margin crops, heat sources can be installed. Nowadays, a system that monitors and warns of frost and the general weather forecast is essential.

In order to be informed about the climate of the premises, the danger of frost or to know the danger of being attacked by different diseases or pests, weather stations such as the ones at WatchDog and their information networks, are indispensable in any property.

Ask us if you want to know what you can do with the stations. WatchDog.