Mastodawn

If you leave food in the microwave oven after the microwave stops, nothing happens (unless you leave it there long enough to get cold)

But, if you leave food in a conventional oven or on a stove burner after they've been turned off, the food continues to cook and might even burn.

"Sunny days, sweeping the clouds away…"

The sun doesn't so much sweep the clouds away as it evaporates them away.