Saturday, June 7, 2014


Thermal Slope
Clouds can develop in response to lifting.

Topographic rises like mountain ranges wring moisture from the air to create orographic clouds.

Orographic comes from a concatenation of the Greek word for hill (όρος) and the Greek verb to write (γραφία).

Orographic lift occurs when moist air is forced upward as it moves over the thermal slope of a rising mountain.

When air rises, it adiabatically cools which raises its relative humidity to cause clouds. Adiabatic cooling occurs when air temperature decreases via a decrease in air pressure caused by volume expansion.

"I know that I am mortal by nature, and ephemeral; but when I trace at my pleasure the windings to and fro of the heavenly bodies I no longer touch the earth with my feet: I stand in the presence of Zeus himself and take my fill of ambrosia."
― Ptolemy, Ptolemy's Almagest