Donald Shymanski, age 13, of  New Bridge., New Jersey, for his question:

What is meant by mean temperature?

It sounds believable when we learn that the mean July temperature of Antarctica is below zero. This kind of weather is mean in the nasty sense, but the word mean has other meanings. When the meteorolgist talks about the mean temperature he is using a word which descended to us from a much older word for middle. The mean temperature is the average temperature to be expected in a certain place through a certain day or month.

A daily mean temperature is the average temperature throughout a 24 hour period. The meteorologist may base the days mean temperature on 24 hourly readings. He is more likely to take the middle point between the highest and lowest temperatures of the period daily mean temperatures are totaled to give weekly and monthly mean temperatures.