This question is in my kids CAT test for 4th grade and I don't even know what the right answer is so I thought I would ask you. The question is: When you see clouds in the sky, you can always know that: A. it will rain B. the air is very cold C. it will soon thunder or D. some water vapor has condensed. I'm thinking D but not too sure now.

MIKE MOSS SAYS:     Judy,    You wer on the right track, and now you can be sure. The answer would be "D." Anytime you can see a cloud in the sky (assuming there hasn't been some kind of chemical release - we're talking about routine, natural clouds here) some water vapor had to condense in order to form the cloud droplets. On the other hand, the other answers are all possibilities but not certainties when clouds are seen. Not every cloud produces rain or lightning and thunder, and of course  we've all seen clouds on warm days and mild days as well as very cold days.