A Tale of Two Winds Monday

There will be two wind systems affecting the United States early this week.

First, the Santa Anas are back.

For an explanation on what Santa Ana winds are and what causes them, let's review what I said in a blog entry last month.

What are Santa Ana Winds? Very simply, they are localized winds that develop in Southern California, blowing westward through the mountains. As they move down the mountains, the wind accelerates to extreme speeds. In the Fall, the Santa Ana Winds often aggravate wildfires by fanning their flames.

There are two websites that can educate you a lot on Santa Ana's if you're interested. One is UCLA's Santa Ana Page, the other is a page at UCSD. UCSD actually runs a "Santa Ana Index" which indicates when Santa Ana winds are likely. Needless to say, it's red today.

On the other side of the mountains, Chinook winds will bring mild air into the Northern Plains on Monday.

These winds take place when moist air (created on the other side) sinks, atmospheric pressure increases, and the air warms. As we used to say in school:

PV=nRT

That translates to Pressure * Volume = n * R (constants) * Temperature (more info for geeks here). What goes up on one side of the equation must go up on the other, so it follows that increasing pressure would increase the temperature of the air (if you don't believe me, click here for a demonstration).