"Those aren't clouds. The good news is, you will rarely need sunscreen."
Hah! I remember when they noticed that after widening opening of the ozone layer over the Antarctic, there were increased skin cancer rates in Chile, except for Santiago, Chile, which had lower
It turned out that the air pollution, including low-level ozone, filtered the UVA/UVB rays.
Good for your skin--not so good for your lungs.
I've heard that there's a Chinese version of Twitter, that also allows 144 characters. But since characters in Chinese (kanji) are full words, you can really express yourself.
Makes it a lot more useful than Twitter, in my mind. I guess there are too many people on the internet with short attention spans.