What shall we call these winds?
By John Lindsey | San Luis Obispo Tribune
Published: November 10, 2012
Throughout the world, downslope winds have been given different names. Along the Rocky Mountains, these down-slope winds are known as Chinook — literally meaning "snow-eater" — winds. In Japan, they are called the Oroshi. Around the Adriatic Sea, they are referred to as the Bora winds.In Southern California, these downslope winds are called the Santa Anas. These famous winds may have gotten their name from the Santa Ana Mountains. However, some Southern Californians believe that the traditional name is Santanas. That name was occasionally used in early reports. In Northern California, these downslope winds are called diablo winds. Even relatively small geographic areas will have their own unique name for these winds.
For example, in Santa Barbara, they're referred to as "sundowners." "The Barber" winds blow over the town of Greymouth in New Zealand.
Like an old International Harvester semi-truck rolling down the Cuesta Grade, air from the higher elevations of the Santa Lucia Mountains will flow downward along the mountain slopes toward the Pacific Ocean, pulled by the never-ending force of gravity.
These are often referred to as downslope or lovingly described by surfers as offshore winds. However, these downslope winds are technically called katabatic wind, from the Greek word katabatikos, which means "going downhill."
As the air mass descends the side of the mountain range, it warms at the rate of about 5.5 degrees Fahrenheit per 1,000 feet of descent. Meteorologists refer to this rate of warming as the dry adiabatic lapse rate. If the air is warm at the top of the mountain range, it can be sizzling hot and bone dry by the time it reaches the valleys below.
You see, as the air molecules descend into the higher atmospheric pressure close to Earth's surface, they gain kinetic energy as they compress inward. If you've ever filled up a bicycle tire or especially a scuba tank, you've probably noticed them getting warmer as the pressure increased. This is
also referred to as compressional heating.
A large ridge of high pressure parked itself over California last week and produced night and morning northeasterly (offshore) winds. These downslope winds along with subsidence, or sinking of the air mass over the county, created the warmest beach weather of the year. Old high
temperature records fell like bowling pins this past Monday and Tuesday.
When these northwesterly (offshore) winds blow, temperatures at our beaches often peak during the late morning hours before the afternoon northwesterly (onshore) winds cool things off.
Historically, wind data recorded at the Diablo Canyon meteorological tower indicates that northeasterly winds blow about 12 percent of the time throughout the year, but during the fall this percentage can increase to more than 20 percent.
Autumn is often the warmest season along our beaches because of the greater occurrence of northeasterly (offshore) winds.
All this leads to an interesting question that Chris Arndt of SLOweather.com asked recently: Why doesn't San Luis Obispo County have its own unique name for these downslope winds?
I don't know the answer. But perhaps it's finally time to name these winds. We could call them the Santa Lucia winds, or perhaps the Obispo winds. Maybe even the Cuesta winds.
Source: http://www.sanluisobispo.com/2012/11/10/2291870/what-shall-we-call-these-winds.html--
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