Scientists use this principle to track humidity with a metric called wet-bulb temperature, in which they wrap a wet, room temperature cloth around a thermometer to see if evaporation will lower the reading.
The authorities in Yemen have freed a student, Hanan al-Samawi, who'd been held on suspicion of sending the parcel bombs found on cargo planes in Britain and Dubai last week.
The United States has handed a stolen Picasso painting to French officials nine months after it was found in a package labeled as a handicraft worth about 30 dollars.