Scientific question(s)

[supermario128]

http://www.nssl.noaa.gov/faq/faq_ltg.php

^That's a great site to learn about lightning, it even answers your question.


Does lightning happen during the winter?

Lightning occurs less frequently in the winter because there is not as much instability and moisture in the atmosphere as there is in the summer. These two ingredients work together to make convective storms that can produce lightning. Without instability and moisture, strong thunderstorms are unlikely.

During the winter, the land surface is cooler because there is not as much heating by the sun to warm it up. Without warm surface temperatures, the near-surface air wouldn't rise in the atmosphere very far. Thus, the kinds of deep (8-15 km deep) thunderstorms that develop in the summertime wouldn't develop.

Warm air holds more water vapor. And, when water vapor condenses into liquid water cloud drops, latent heat is released which fuels the thunderstorm. So, warm, moist air near the surface (and the proper conditions aloft to give you lots of instability) can result in deep convection, which may produce lightning discharges.

Clouds become electrified when strong updrafts (fueled by the instability and moisture) bring supercooled liquid water drops and ice crystals at temperatures less than freezing (0 deg C) together. In this environment, interactions between the ice crystals and supercooled water droplets produce electric charges. The exact mechanisms by which this charging happens remain unknown. The electrical charges build up until they are strong enough to overcome the resistance of the surrounding air. The breakdown of the electric fields produced by these charges is the lightning bolt.