system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why does it thunder when it rains but almost never when it snows?
gpt
Lightning (and the resulting thunder) typically occur in an unstable atmosphere.  An unstable atmosphere occurs when cool air is above warm air (warm air rises).  This is a very common thing to happen during the summer in the United States, thus we hear a lot of thunder here.  During the winter, the atmosphere is typically stable. Most snowfall events occur with cold air at the ground and warmer air aloft, so there is rarely instability required for lightning and thunder. (Disclaimer: This is an extremely general explanation.  Specifically, lightning is caused by charge separation in the cloud, but the processes that create this charge separation are not fully understood)