I have a question about my watch which has been bugging me for a little while, and I was wondering if anyone could enlighten me as to the physics behind it. One day a while back I went out for a run in the rain and some water got into my watch, behind the glass. I only noticed because it had condensed on the glass and was making the watch face blurry. I thought I'd ruined the watch but the next day, the water droplets had vanished, so I thought they'd managed to find their way out of the watch, but no - some time later, they reappeared again. And now, every now and then the glass gets steamed up (but only in the middle), on seemingly random days. Temperature doesn't seem to have much impact (it's steamed up today and it's about 15 degrees, but it also steamed up last week when it was really hot), so I was wondering if it might be something to do with changes in atmospheric pressure? I might be barking up completely the wrong tree, but if anyone can explain it to me that would be great. Thanks!