Wednesday, July 10, 2013

How Much Do Clouds Weigh? Thoughts While Flying From LA to Anchorage

As I flew from LA to Anchorage last night clouds covered the water below most of the way.  We left as the sun was setting in LA, about 8pm.  But as you'll see it never got dark as we flew north and as we landed in Anchorage about 40 minutes early at 11:20pm, despite a moderate cloud cover, it was totally light out.  I love summers here.

Santa Monica Bay

Click to enlarge this google map
The water was already rising from the sea as we took off.  Along the Santa Monica Mountains in the background fog was already up.  Here, just west of the airport, looking north, it was mostly clear with just a hint of the evaporation.  The canal like object is the outlet to the sea from Marina del Rey.  I'd ridden my bike to sea side end of the northern jetty just before getting ready to get the Lincoln bus to the airport.  Venice Beach lies
north of the marina.

I hadn't been on the non-stop flight for a while and forgot it stayed mostly over water.  I began to think of all that water migrating up from the ocean surface and hanging in the air.  The little girl in front of me talked about bouncing on the clouds. 

Here's a view along the beach front that ends at the marina.  This is the tonier end of Venice south of Washington.  The bike path from Santa Monica, through Venice, ends at Washington - at the pier - and you have to take the streets to Top Sail, when a path begins again to the marina.  Before Venice Blvd is the carnival like area of the boardwalk with lots of people.  From Venice (going south) to Washington, the frontage is homes, including the Frank Gehry home, not shops along the bike trail.

I'm assuming the folks south of Washington didn't want the riff-raff so they didn't let the bike trail continue past their beach front homes.  But that's just a guess and I've learned our assumptions are often way off.  Only when you get several blocks from the jetty of Marina del Ray, does a path reappear, and you can see it was pretty empty on a warm July Tuesday afternoon when the norther parts of the trail were packed.

A little up the coast, ocean was covered in clouds and moisture had seeped in between the the mountain.

Further north the upper clouds turned pink and the lower ones, looking a bit like ice, were white.  I started wondering what percent of the ocean might be clouds right now.  I figured that was probably a very small number.

But today, I decided to see if I could find it.  Someone had emailed me a link to an article about Wolfram Alpha

Engine Outside Window Glowing and Not
Wolfram Alpha is probably the most useful site on the internet.
It's not a search engine, it's not an encyclopedia, and it's not a calculator, but it's a little bit of all of that. It's really the only member of its field.
Originally developed as an online version of Stephen Wolfram's Mathematica software, its basic functionality is that of a math equation solver.
Over the years, however, it's grown substantially, and has really matured as a site to become one of the coolest and most informative sites online.
Here are some of the coolest things you can do with it.

It had a list of interesting things you could  ask it to calculate.  So I asked what percent of the ocean was in clouds.  It couldn't figure out what I was asking.  I tried a few others and finally, how much do clouds weight?  Here's the answer I got:

I could have given that answer myself.  So I went back to google and got a few other answers:

From the Smithsonian:
"How much water is in a cloud? What would be left if you squeezed the water out of it?
Jerry Jones
Eugene, Oregon

It depends on the cloud. A giant thunderhead may contain more than two billion pounds of water, but even a modest-sized cloud may contain water equivalent to the mass of a 747 jet. If you could squeeze the water out, the cloud would disappear. But you can’t. Some desert peoples use cloth “cloud catchers” to gather condensation and fill local water tanks for drinking and irrigation.
Doug Herman
Geographer, National Museum of the American Indian"
The USGS offered this bit of trivia on its Water Cycle page:

Care to guess how many gallons of water fall when 1 inch (2.5 cm) of rain falls on 1 acre of land?
When you clicked to see the answer it was 27,154 gallons of water.  Is that a lot?  How many Olympic sized swimming pools would that fit?  *Answer at bottom.

The USGS page on Water Storage in the Atmosphere came a little closer to answering my original question.  (It also answers in more detail the 2 billion pounds answer above.)  It also had this chart.

Global distribution of atmospheric water

One estimate of global water distribution
Water sourceWater volume, in cubic milesWater volume, in cubic kilometersPercent of total freshwaterPercent of total water
Total global fresh water8,404,00035,030,000100%2.5%
Total global water332,500,0001,386,000,000--100%
Source: Gleick, P. H., 1996: Water resources. In Encyclopedia of Climate and Weather, ed. by S. H. Schneider, Oxford University Press, New York, vol. 2, pp.817-823.
So, he estimates that .001% of total water on earth is in the atmosphere.  That doesn't seem like much, but when you consider how much of the earth is covered by ocean and how deep that ocean is, it's quite a bit.

From How Stuff Works (I can't find anything on this site that talks about where their information comes from and there's no author listed for this article, so be skeptical.)

The oceans are huge. About 70 percent of the planet is covered in ocean, and the average depth of the ocean is several thousand feet (about 1,000 meters). Ninety-eight percent of the water on the planet is in the oceans, and therefore is unusable for drinking because of the salt. About 2 percent of the planet's water is fresh, but 1.6 percent of the planet's water is locked up in the polar ice caps and glaciers. Another 0.36 percent is found underground in aquifers and wells. Only about 0.036 percent of the planet's total water supply is found in lakes and rivers. That's still thousands of trillions of gallons, but it's a very small amount compared to all the water available.The rest of the water on the planet is either floating in the air as clouds and water vapor, or is locked up in plants and animals (your body is 65 percent water, so if you weigh 100 pounds, 65 pounds of you is water!).

As we got further north, the sun was back in play.

I've discussed Edward O. Wilson's book The Future of Life before.   A key argument he makes is that the earth's natural systems are a huge infrastructure project - redistributing water, cleaning air and water, developing good soils, and lots of other things that men pay little attention to when they dam rivers, pollute oceans, cut trees, etc.

I think the notion of moving the huge amounts of water from the ocean to the clouds and out over the land where it comes down as rain or snow should give us pause.  Humans are working hard to find reasonably priced desalination processes.  And here nature does it for us effortlessly.  We just have to stop polluting the source and then polluting and otherwise wasting the water that the clouds provide free of charge.  

*ANSWER:  The Region 8 EPA says an Olympic sized pool holds 630,000 gallons of water, so 1 inch of water on one acre wouldn't do much to fill it. 

And since water weighs 8.34 pounds/gallon the 2 billion pounds of water in a thunder cloud mentioned above comes to about 240 million gallons, or a lot more than what you need to fill an Olympic sized pool. 

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