A snowstorm with lightning may occur, but this is not the most common occurrence. They occur more frequently at the end of winter or at the beginning of spring. This is due to the existence of marked temperature gradients and strong winds in the upper atmosphere.
In order to understand why this occurs, we will detail the factors necessary for an electrical discharge to occur.
HUMIDITY
During the summer months, warm, moist air fills the troposphere. Above the troposphere, the air is colder and has a large amount of ice crystals. As the warm air rises, water vapor condenses into water droplets. As these water droplets rub against the crystals in the upper layers, an electric field appears in the cloud.
The positive charges are piled up on the cloud and the negative charges are piled up in the lower part of the cloud. When the difference between the two charges is significant, lightning occurs.
In winter the air does not contain much humidity, and it is the lack of humidity that prevents thunderstorms from occurring.
INESTABILITY
Instability occurs when warm air from the Earth’s surface rises due to convection. In summer, for example, this occurs when it is very sunny and the ground is so hot that it heats the ambient air.
As the warm air rises, cold air descends. When the rising air currents reach the upper troposphere, the air cools and condenses.
In winter, there is less sunlight and the environment is colder, which means that the ground is less warm, there is less convection and the chances of a thunderstorm are reduced.
TRIGGERING MECHANISMS
There are numerous triggering mechanisms: a front, a squall, an isolated depression at high levels (DANA), an orographic relief…
