130 degrees- 

                 Howdy! My name is Christopher Duvall, and I am a OneSky Weather Specialist
                 for this group. I am a meteorologist at Rutgers University in New Jersey. Nice to
                 meet you! 

                 A. Deserts: 

                 Deserts are defined as areas where there is a lot less moisture being added to the
                 ground each year than is evaporated from the ground back into the air. In other
                 words, deserts are places where there isn't very much moisture such as rain,
                 snow, dew, or frost available for the ground to absorb and therefore be able to
                 support life. Deserts could be sandy or rocky, flat or hilly, but one thing is for
                 sure- they will not have a lot of vegetation because the ground does not have a
                 lot of water available for life to grow. 

                 Deserts form due to several reasons usually related to geography. For example,
                 deserts could form due to mountains nearby, which block moist air from blowing
                 over the area. This is called a "rain shadow". Areas where the air is seldom lifted
                 up, so clouds and then rain could form, may also be desert areas. 

                 Since deserts usually have dry air, they have among the widest ranges in
                 temperature from day to night in the world. Dry air warms and cools more
                 quickly than moist air, which is why Phoenix, Arizona gets up to 115 degrees F in
                 the summer but drops down to 60 degrees F at night. 

                 So if dry areas have temperatures that are very different between day and night,
                 what do you think a moist area such as Florida would be like? Yup. Florida's
                 temperature changes much less between day and night- perhaps it is 90 degrees
                 in the afternoon but 75 degrees at midnight. 

                 Challenge: 
                 Find the desert areas around the world and try to determine why there is a desert
                 in that area. Think about which direction the air blows over that area, and where
                 the air goes before it reaches the desert. 

                 B. Precipitation: 

                 I have posted other messages that describe precipitation for students who have
                 asked similar questions. Please see the message titled: 

                 " **Precipitation and Hail** " 

                 There are also other messages posted by Weather Specialists that may help to
                 explain deserts and precipitation. 

                 If you have any other questions, please let us know. 

                 Hope this helps! 

                 - CD 2/24/2000