I camped the Sierras in both summer and winter.  Summer was mostly in Yosemite in the valley of the Tuolumne but I didn't take a camera and don't have any pictures of that area.  Winter camping was more difficult (and dangerous) and I only did that with a group.  Even then, you could get caught.  For example, you might come upon a stream in the early morning and cross it easily - water would be barely trickling in the stream.   But when you came back in the afternoon, it was a raging torrent and there was no way to cross it, especially in winter when you dare not get wet.  The reason for the change is that the sun would melt quite a bit of snow during the day, causing the streams to swell significantly.  But after a cold night, the melting would stop and the stream would go back to a trickle.  So you had to be prepared to spend the night when you hadn't planned on it.  As long as a snow storm wasn't coming in, it was no problem.  But if a storm was blowing in, you had best be able to withstand several days being trapped in camp, hoping your tent would not blow away. 

Here's some pictures of a group of us snowshoeing in the sierras, close to where the Donner party were trapped for the winter, and a camp set up in the snow.