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Razor thin marine layer: the science & the beauty

 
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windfind



Joined: 18 Mar 1997
Posts: 1323

PostPosted: Fri Oct 27, 2017 11:12 am    Post subject: Razor thin marine layer: the science & the beauty Reply with quote

Hi Gang,

Fall brings shorter days and a more acute angle of the sun so the pressure gradients are weaker. And up at ≈ 18,000 ft. the high pressure system ridge below has pancaked the marine layer. Together these events mean weak wind. The top 2 images show this from a scientific perspective. But the following photos show its beauty as seen from cams this morning.

http://blog.weatherflow.com/west-coast-wind-blog-the-science-and-the-beauty/

Mike Godsey
iwindsurf.com/ikitesurf.com
Weatheflow.com



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ctuna



Joined: 27 Jun 1995
Posts: 742
Location: Santa Cruz Ca

PostPosted: Fri Oct 27, 2017 10:31 pm    Post subject: Reply with quote

Nice pictures of the Bay.
Is it possible for us to access that wind speed and direction
but altitude or is that not publicly available.
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ethurlow



Joined: 07 Dec 2002
Posts: 110

PostPosted: Sat Oct 28, 2017 9:59 am    Post subject: Reply with quote

Interesting, looks like a very slight wind moving fog Westward.
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windfind



Joined: 18 Mar 1997
Posts: 1323

PostPosted: Sat Oct 28, 2017 12:20 pm    Post subject: Reply with quote

Hi Ctuna & Ernie,

Here is the link to the Bodega 449 MHz profiler:

http://met.nps.edu/~lind/profiler/bby_915.gif

There is a similar profiler at Ft. Ord which would help in the Santa Cruz zone. Notice on the X axis that time goes from right to left so the most current reading is on the left. Cooler marine air is in blue. The warmer air of the inversion in in yellow to red.

The stronger the demarcation between the blue and the yellow the stronger the inversion and the more compact the marine layer.

The Y axis gives you the depth of the marine layer.

The winds barbs give you the direction and velocity of the winds aloft at different levels.

Since this sensor is at Bodega it is of limited usefulness inside the Bay. But it does give you the trend of the marine layer and the winds aloft. This is especially useful in the spring when there are strong NW winds just aloft and in the Fall when there are unfavorable NE winds aloft.

Ernie is right about the faint westerly winds in the photos. The marine layer is extremely shallow because high pressure at ≈ 18,000 ft. is compressing the marine layer clouds. You can see this in both the profiler image and in the photos. Who can explain why the bulge in the clouds over Alcatraz?

Mike Godsey
iwindsurf.com/ikitesurf.com
Weatheflow.com
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ethurlow



Joined: 07 Dec 2002
Posts: 110

PostPosted: Sat Oct 28, 2017 2:05 pm    Post subject: Reply with quote

Maybe several affects due to land/water temperature differences. Maybe condensation/dew point temp mostly near the leading edge of the island and then, since sun has just risen then local radiation for most of land surface causing convection (up) downstream?

Ernie
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windfind



Joined: 18 Mar 1997
Posts: 1323

PostPosted: Fri Nov 03, 2017 8:52 am    Post subject: Reply with quote

Hi Ernie,

It is mostly a dew point phenomena. It is common to see such a cap on Angel Island in the summer when the marine layer is thin.

Mike
iwindsurf.com/ikitesurf.com
Weatheflow.com
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