Why do foreigners meet and ask about the weather?

Customs and habits, such as China people love to ask if they have eaten when they meet. The expression of foreigners is relatively straightforward, so if you ask if you have eaten, you will say that you have eaten. If you don't eat, say you haven't eaten. If they say they didn't eat, you have to invite them to dinner. Hehe, so they don't ask if they have eaten. In addition, foreigners usually avoid talking about other people's privacy, such as salary.