What do the two speakers have in common?

W: Welcome back! I didn’t see you in math class on Friday.
M: I wasn’t here on Friday. My geography class went on a field trip to look at some of the different rock formations here in California. Our last stop was Death Valley. In fact, we camped there last night.
W: Death Valley! But that’s desert! Wasn’t it much too hot for camping?
M: No, not really. It gets hot during the day, but it cools off very quickly at night. There’s no moisture in the air to hold the heat after the sun goes down. If it were humid, it would stay hot all night.
W: Well, did you enjoy the trip?
M: It was fascinating. The desert is nicer than you might think. Since there is so little vegetation growing, it’s very easy to see different kinds of rocks.