The Last Word on Nothing blog has a long explanation of the cultural and scientific importance of June Gloom--the infamous weather phenomenon that casts a very un-SoCal pall over the coastal region every spring and summer, prompting shock in newcomers and visitors. The recipe for June Gloom requires three ingredients: cold Pacific Ocean water, an ocean current known as the California Current, and a high pressure formation known as the Pacific High: "Usually, the atmosphere gets colder as you head up. But the cold water creates a situation where the air near the water's surface is colder than the air above it: an inversion. The Pacific High pushes air downward, compressing it and warming it. Together, this forms a stable inversion air that can hold a layer of cloud near the water's surface like an older brother crouching on an upstart sibling."
Here are a few more fun facts about June Gloom (and its more official pseudonym, the Marine Layer):
-- Like the movie industry, June Gloom is also found in the Pacific Northwest, however it's more conspicuous in LA.
-- Chronological variations on June Gloom: May Gray, No-sky July, and Fogust.
-- The Marine Layer is made up of low altitude stratus clouds. According to the Scripps Institute of Oceanography: "Stratus type clouds are sheet like clouds with close to horizontally uniform base and top. They generally extend for large distances horizontally (10-100s of kms), but are relatively shallow in depth usually (usually 500-2000 meters)."
-- From LWON: "The gloom is the home of a wild kind of cloud field called actinoform clouds, which, to a satellite's eye, look like enormous leaves or pinwheels."
-- "Lodide released by kelp may turn into cloud condensation nuclei, which could make clouds thicker and more pervasive."
-- Scripps holds a contest every year to guess the amount of June Gloom days for the year (Science isn't very good at predicting June Gloom, despite the climate science industry's best efforts).
· June Gloom [The Last Word on Nothing]
· What are Marine Layer Clouds and How Do they Form? [Scripps Institute of Oceanography]