Atmosphere in the age of dinosaurs

Dear Tom,
What is the most unusual question that you have ever answered?
-Jim Oosner
Dear Jim,
This one from Dave Nelson in Evanston stands out: While enjoying a bright blue sky the
other day with puffy white cumulus clouds, I wondered: Am I looking at a sky and cloud
scape that a dinosaur might have observed 100 million years ago? The reply: Dinosaurs
lived from 245 million to 65 million years ago, and the same kinds of cumulus clouds
that you observe in our present-day summer sky assuredly populated the dinosaurs’
sky as well. The laws of atmospheric physics are immutable. Even assuming the
gaseous composition of the Earth's atmosphere was somewhat different during the age
of the dinosaurs, the nature of water vapor and the atmospheric processes that produce
cumulus clouds have not changed with time.