Ticker for June 23, 2008

                
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June 23, 2008      June 23, 2008      June 23, 2008      June 23, 2008



More Ticker Fundamentals!

Last week, we started a mini-series based on hard-hitting weather
fundamentals questions from one of last week's subscribers ("Ann").

So, we all talked about wind, and how it was mostly related to
pressure gradients. Here's a good place to work in Ann's next
question:
"Why does Oklahoma wind come from all points of the compass?"

The answer has to do with those pressure gradients we discussed last
week. As the systems that govern wind spin up, move, and die off,
they can take up a number of positions relative to Oklahoma. And,
for wind direction, it's the position of the pressure systems that
plays the biggest factor.

The rule of thumb is that if you stand with the wind at your back,
low pressure will be to your left, and high pressure to your right:



Another way of thinking about this: if you stand and face the low
pressure, wind will blow from your left to right. Now, if the
position of that low pressure system moves, so too does the wind
direction.

It turns out that there are some preferred positions for developing
pressure systems. We're using "preferred" here as "occurs more
frequently than elsewhere, but certainly not always. There are
also preferred directions for their movement. So, there are certain
preferred directions for wind.

You can see this for yourself in a "wind rose" for an Oklahoma
Mesonet station (we chose Stillwater):



On a wind rose, each "petal" describes how often the wind blows from
that direction. You can see that southerly winds rule the roost at
Stillwater (and the rest of Oklahoma, for that matter). Easterly and
westerly winds are actually somewhat rare!

Here's a text table that contains all of the data that went into
this wind rose:

https://content.mesonet.org/ticker/archive/20080623/STIL.ann.txt

The numbers in each cell represent how often the wind blows from
that direction, at that speed.