Flying in the sky during daytime and looking at the horizon. On the top the sky, a perfect blue with a color gradient from ocean blue to blue, then the horizon, a beautiful line with color gradient from sky blue to white. I don't know if the image will get displayed but like this (I took it a couple of months ago): And this:

And also looking at the clouds in the mountains before a typhoon, I always felt humbled when I was looking at it.