If the temperature is 40c at ground level what is the temp at 1m 1.5m 2m?

Go to google.com and search "air well". A lot of people have tried to invent a water catcher that works on ambient temperatures and air movements. The best was a large building of rocks that cooled at night and condensed water in the day. Performance of all such designs is poor, even in ideal locations. Other designs are called "fog catchers" and they pull water from air with a nylon mesh. The design is around 30 feet tall and twice that wide, but at least it does actually produce a usable amount of water; tens of liters per day.