The Hidden Beauty of Atmospheric Water Vapor

In many ways, meteorologists are in the art business, because many images produced by our models and observing systems are simply beautiful in their own right.  Many could be framed and would provide esthetic pleasure to most viewers.

Perhaps among the most beautiful types of meteorological imagery are the satellite depictions of atmospheric water vapor.  Let me show you.

Water vapor is a clear gas that is invisible to the naked eye.

When you see a typical satellite image in the visible part of the spectrum (example below from today), you see the light from the sun reflected off the surface and clouds.   Water vapor in the atmosphere does not interact with visible light and so you can't see it. 

Water vapor does interact with radiation in the infrared portion of the electromagnetic spectrum, where it both absorbs and emits radiation.

NOAA GOES weather satellites have the capability of viewing the emission of water in the atmosphere.  In fact, the latest GOES satellites can look at water vapor in three wavelengths, which can tell us about the amount of water vapor in the upper, middle, and lower portions of the atmosphere (mostly in the troposphere, the lowest layer of the atmosphere where all the weather takes place.

For example, here is the water vapor in the upper part of the atmosphere (6.2 micron wavelength, micron is a millionth of a meter), with blue being small values and green the most.  All kinds of amazing swirls associated with atmospheric circulations.  Lots of moisture in the tropics and dry zones in the subtropics.

Using a slightly longer wavelength (6.9 microns) we can see water vapor in the middle portion of the troposphere (using roughly 6.9 microns).  In this image, the driest air includes the yellows and orange colors, with green colors being very moist.   Stunning image.

These images are impressive even in black and white, as illustrated by the water vapor image on July 12th.  You can see an upper level cyclone north of Hawaii (the swirl of clouds) and the very, white blobs associated with thunderstorms.

Knowing about these structures are very useful for meteorologists--telling us about circulations not apparent in other wavelengths.   And the water vapor structures can be used to inform our numerical weather prediction models regarding the three-dimensional structure of the atmosphere, which contributes to better forecasts.

Both beautiful and practical:  it doesn't get much better than that!

Tonight is perhaps the best night yet to see Comet Neowise

You can probably tell by now that I am quite interested in astronomy... in fact, one of the most difficult decisions of my life was deciding between astronomy and atmospheric sciences..  I tried to bridge the gap by studying both as an undergraduate and working with Carl Sagan on modeling the Martian atmosphere.  But in the end, I went for atmospheric sciences.

Anyway, tonight may be the best night yet to view Comet Neowise.  The sky is quite clear, with only a few thin cirrus clouds (see below).

The atmosphere is very, very clean.   The Seattle PanoCam shows excellent visibility:

And the latest air quality measurements show extremely clean air.  Looking at the particulates over Seattle, the values (PM2.5) are under 10 micrograms per meter cubed.   Take a deep breath--this is the good stuff.

Sunset tonight is 9 PM.   My advice is wait until 10:45 PM to look, and it would be better to wait until 11:00 PM.   Astronomical twilight doesn't end until 11:35 PM...so there will be slight light in the sky until that time.  Amazing, isn't it?

Look to the Northwest in the lower sky under the Big Dipper (see figure from Stardate.org below)

Professional Tip:  If you are having trouble finding the comet, take a picture of the sky with your smartphone (turn the flash off).  The cameras in most smartphones are more sensitive than your eye.  Then look at the image you have taken.  It may shock you--the COMET will be there!

Professional Tip2:  Use your peripheral vision to find the comet, the center portion of the retina is not as light sensitive strangely enough.

Good comet hunting!