Relative humidity is the ratio of the current absolute humidity to the highest possible absolute humidity (which depends on the current air temperature). A reading of 100 percent relative humidity means that the air is totally saturated with water vapor and cannot hold any more, creating the possibility of rain
A push factor would be something like war or famine or something. A pull factor would be something like a job or new opportunity, its usually for financial reasons in my opinion. Hope this helped!
