Update: For what it's worth, Vox has an article about Harvey, and they say it deposited 14-15 trillion gallons of water. Each gallon is 3.78 kg, meaning that the total mass of water deposited for 14 trillion gallons is 5.3e10 metric tons. How's that for estimating accuracy in the above?
Friday, August 25, 2017
Hurricanes, heat engines, etc.
Looks like it's going to be a wet few days, with the arrival of Harvey. I've mentioned previously that hurricanes and tropical storm systems are heat engines - they basically use the temperature difference between the heated water in the ocean and the cooler air in the upper atmosphere to drive enormous flows of matter (air currents, water in vapor and liquid form). A great explanation of how this works is here. Even with very crude calculations one can see that the power involved in a relatively small tropical rain event is thousands GW, hundreds of times greater than the power demands of a major city. Scaling up to a hurricane, you arrive at truly astonishing numbers. It's likely that Harvey is churning along at an average power some 200 times greater than the electrical generating capacity of the planet (!). Conservative predictions right now are for total rainfall of maybe 40 cm across an area the size of the state of Louisiana, which would be a total amount of 5.2e10 metric tons of water. Amazing. I'm planning to write more in the future about some of this, time permitting.
Update: For what it's worth, Vox has an article about Harvey, and they say it deposited 14-15 trillion gallons of water. Each gallon is 3.78 kg, meaning that the total mass of water deposited for 14 trillion gallons is 5.3e10 metric tons. How's that for estimating accuracy in the above?
Update: For what it's worth, Vox has an article about Harvey, and they say it deposited 14-15 trillion gallons of water. Each gallon is 3.78 kg, meaning that the total mass of water deposited for 14 trillion gallons is 5.3e10 metric tons. How's that for estimating accuracy in the above?
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11 comments:
Stay safe and dry Doug!
That's the plan :-)
Doug, hope you are doing (relatively) fine - the images from Houston are horrible.
We are rooting for Houston; hoping that the storm finally moves farther away, spreading the water out more.
Hope you and your lab stay dry. I seem to remember the scopes were below ground level.
Thanks, folks. My family and I are fine, though our cars are not. The basement level labs were all dry as of yesterday, and the campus is actually in quite good shape (though I haven't gotten over there myself).
Doug,
I would like to donate to help out, and I was going to do that to the Red Cross. I see now however that a Greater Houston Community Foundation was mentioned by the Houston Mayor as an avenue to help. I thought a local outfit could be more efficient/useful in the short term.
On their website I can't find data on how much of every dollar actually gets spent on "help" (instead of overhead).
Do you know whether this outfit which apparently exists for a while already (nice website, no info on Harvey) is decent?
Hi - thanks for your generosity and willingness to help. Here is some of their financial data. Looks good, assuming they are trustworthy in their 990 forms.
https://donorhouston.guidestar.org/profile/1148817/greater-houston-community-foundation.aspx
It's not generosity when I'd like to receive help if I end up in a similar situation... It's taking responsibility with decency.
But their data look better than the red cross. So I'll give my drop in the bucket.
Thanks
Hey, Doug, this is Jenny, glad to see you updated the blog! how are the rest of the group? Hope everyone is fine.
Regarding your update: nice!
(if one does not think about the absolute value of the error.... 3e9 tons of water is still a lot :p)
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