When does it rain?

Seriously, I'll be sitting at my desk, reading or whatever, I'll get up and look out the window, It's completely dry and cloudless. I'll sit back down again for awhile, get up again and look out the window, and the ground is all wet and it's cloudy. What gives? Why don't I notice the water falling out of the sky? It's not like I close my shades or anything. I really love to watch rain fall. I hate seeing the evidence of rain that's passed. It's depressing; I'd much rather see it happening, and I keep on missing it! I'll just have to sit outside ALL DAY EVERY DAY so I can experience the rain.