Add Yahoo as a preferred source to see more of our stories on Google. A what? A sling psychrometer is a difficult word for a very simple tool. It dates back to the 1700s and is actually still used ...

An e-mail from a Moline reader recalls an instrument using thermometers to determine humidity and wants to know what it is. It's called a sling psychrometer and consists of two thermometers which are ...

This segment originally appeared in today's edition of the Morning Brief newsletter. Sign up here to get weekday updates from The Weather Channel and our meteorologists. A what? A sling psychrometer ...