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Treating scientists as bags of mostly water

By: Dr. Jeff Masters, 4:01 PM GMT on December 26, 2007

During the holiday season, it's natural to ask philosophical questions such as, "what is the essence of being human?" Well, one way to answer that question is purely scientifically. Humans are mostly water (ugly bags of mostly water, according to Microbrain, Stardate 41463.9, Star Trek: The Next Generation,, Episode 17). More than half the human body is made up of water, and we can use that fact to measure how many humans are present at large gatherings. Such an experiment was performed at the 2006 American Geophysical Union (AGU) meeting in San Francisco, as reported in a November 2007 paper by Darin Desilets et al. of the University of Arizona. The experiment made use of the fact that cosmic rays are continually bombarding the earth, creating fast neutrons as a by-product of nuclear disintegrations. When these neutrons encounter large concentrations of hydrogen (such as found in ugly bags of mostly water), they get scattered. One can look at the resulting scattering pattern and deduce how much hydrogen is present, and make an estimation of the number of people present.

Figure 1. Ugly bag of mostly water (and co-founder of the Weather Underground) Perry Samson (right) poses in front of his Poster at the 2007 AGU meeting. Also pictured: Russ Rew and Mohan Ramamurthy of Unidata. Fast cosmic ray neutrons scattered from their bodies were used to help estimate the number of people present at the 2006 meeting.

The equipment needed to do so costs about $10,000, and was set up in the Moscone Convention Center in San Francisco during the 2006 AGU meeting. The scientists were able to show when lunch breaks occurred by pointing out a sharp reduction in neutron scattering when all the scientists filed out to grab a bite to eat. Desilets et al. estimated about 1,700 scientists were present in the Exhibit Hall of the convention center during the height of the conference, which is probably a reasonable estimate, given the stated capacity of 3575 people. The technique can also be used to perform measurements of water content of snow and soil, and Desilets et al. advertise that they are open to paid invitations to count crowds at Rio de Janerio's Carnival, Pamplona's running of the bulls, and the next World Cup Finals.

Happy New Year, everyone! I'll be back with a new blog on January 2.

Jeff Masters

Desliets, D., M. Zreda, T. Ferre, 2007, Scientist Water Equivalent Measured With Cosmic Rays at 2006 AGU Fall Meeting, EOS, TRANSACTIONS AMERICAN GEOPHYSICAL UNION, VOL. 88, NO. 48, PAGE 521, 2007.


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

95L looks kind of like a comma, Andrea looked like a doughnut.
Here's an interesting loop that shows the evolution of the storm.

I know you guys like the SSD site but now that its down (what a surprise!) i have water vapor imagery that you can use. I think its sometimes better that the SSD site.
AMSU-E Microwave Data showing cloud liquid water.
Notice how 95L is taping into tropical moisture.

Thanks for the link!

: )
Good observation W456. Given the strong inflow at the surface and the upper level trough carrying moisture from South America (through upper level diffluence) is helping the system.
Infrared Imagery with surface temps overlay

M represents a station, buoy or ship that did not reported in the last 2 hrs. From the few observations...uniform surface temps.

This shows the storms's evolution very well

493. StormW 8:43 AM PST on December 29, 2007
477. Weather456 11:23 AM EST on December 29, 2007
So taz to answer ur question

4960m is about the 300 mb level.

I can tell you that some past upper lows at that intensity have had -46C at 300 mb. If you were to bring that down to the surface using a standard adiabatic lapse rate..that would be 2C at the surface.

Now factor in the Oceanic Modifier, WAA, vegetation and the forecast snow cover. Then compare it with average.

10-20C near the coast and low valleys of CA
below Zero at higher elevations

Or, for a real general comparison...figure the 540 or 5400 line usually depicts the freezing line (0C or 32F)

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