top of page

The skinny on cloud streets

Updated: Nov 1, 2021

If you were flying over the clouds below, what do they tell you about the (in)stability above and below these clouds as well as the wind direction?

Seasoned glider pilots learn how to read the clouds. Certain clouds imply the potential for lift and they can also tell the glider pilot about the direction of flow of the air aloft. Take a look at the visible satellite image below (the Florida peninsula is on the lower right with Texas on the left). What do these clouds tell you about the environment within the planetary boundary layer (PBL)?

They actually tell you quite a bit. Cloud streets pictured above (yes, you read that correct - streets, not streaks) are lines or rows of cumulus clouds (shallow, moist convection) that hang out near the top of the mixed layer. The mixed layer shown in the Skew-T log (p) diagram below is the turbulent unstable layer influenced by the Earth's surface. These cloud streets tell you that the lapse rate near the surface will have a dry adiabatic lapse rate (3 degrees Celsius for every 1,000 feet gain in altitude). Bases of the cumuliform clouds will typically form just above the lifted condensation level or LCL which is normally right near the top of the mixed layer.