Why isn't there lightning when it snows?
It's not a coincidence that we see a lot less lightning and hear a lot less thunder when it's snowing than when it's raining. It's because of the same reason you need to wear a hat, coat, and mittens to go outside in the snow: it's really cold out!
The big thunderstorm clouds are caused by rising warm air. Warm air is actually lighter than cold air because when the temperature drops, the invisible gases that make up air get packed together more tightly. Cold air sinks below warm air, and the warm air rises up. However, when the air is very cold, like during a snowstorm, the warm air doesn't rise as much, and those thunderstorm clouds don't form as easily.
It is possible to have thunder and lightning during a snowstorm. It's called "thundersnow," and it is pretty rare. Some cool things happen during thundersnow. Lightning causes all the snow in the sky to light up, and it reflects the lightning brightly through the sky. The snow also causes the thunder to be muted. The thunder gets very quiet.
The lightning that happens during thundersnow is just as dangerous as regular lightning, so you don't want to be outside when it happens.
Exploration
Thunder in the Distance
Did you know you can actually get a pretty good idea of how far away lightning is by counting the seconds between the lightning flash and the thunder that follows it?
As soon as you see the lightning, start counting the seconds (1 second, 2 seconds, 3 seconds, 4 seconds...) Every time you count to 5 seconds, the thunder is about one mile away. If you count to ten seconds, the lightning is about 2 miles away. If you count to 15 seconds, it's about 3 miles away.
Think about how you would be able to tell that the lightning is getting farther away. How would you be able to tell that it is getting closer?