A “Fallstreak Hole” is seen Saturday over South Bay Boulevard. These holes are usually formed in altocumulus clouds when an aircraft cuts through them. From time to time, water droplets in such a cloud layer can be “supercooled,” dropping to a temperature below 32 degrees even though they have not frozen yet. When an aircraft flies through these clouds, air pressure momentarily drops as the supercooled water droplets pass over the aircraft wings, causing an immediate drop in air temperature. This can be just enough to cause the droplets to freeze suddenly, creating a chain reaction: When they freeze, they release latent heat, which causes the air to expand and rise, like a hot-air balloon. The surrounding air sinks in response to this rising air, producing this type of cloud formation.
A “Fallstreak Hole” is seen Saturday over South Bay Boulevard. These holes are usually formed in altocumulus clouds when an aircraft cuts through them. From time to time, water droplets in such a cloud layer can be “supercooled,” dropping to a temperature below 32 degrees even though they have not frozen yet. When an aircraft flies through these clouds, air pressure momentarily drops as the supercooled water droplets pass over the aircraft wings, causing an immediate drop in air temperature. This can be just enough to cause the droplets to freeze suddenly, creating a chain reaction: When they freeze, they release latent heat, which causes the air to expand and rise, like a hot-air balloon. The surrounding air sinks in response to this rising air, producing this type of cloud formation. John Lindsey
A “Fallstreak Hole” is seen Saturday over South Bay Boulevard. These holes are usually formed in altocumulus clouds when an aircraft cuts through them. From time to time, water droplets in such a cloud layer can be “supercooled,” dropping to a temperature below 32 degrees even though they have not frozen yet. When an aircraft flies through these clouds, air pressure momentarily drops as the supercooled water droplets pass over the aircraft wings, causing an immediate drop in air temperature. This can be just enough to cause the droplets to freeze suddenly, creating a chain reaction: When they freeze, they release latent heat, which causes the air to expand and rise, like a hot-air balloon. The surrounding air sinks in response to this rising air, producing this type of cloud formation. John Lindsey

SLO County weather forecast for the week of Sept. 4

September 03, 2017 12:21 PM