The World From Your Airplane Window
A science writer's guide for the inquisitive air traveler.
- By Brian Clegg
- AirSpaceMag.com, February 07, 2012
Muhammad Mahdi Karim
So far the view has been superb. But at some point on the journey you're likely to pass into cloud. Clouds are divided by type [here stratocumulus mix with cumulus in the foreground, with cumulus beyond]. These correspond both to the height at which the cloud is located and the shape and density of the cloud. There are technically a great number of cloud types—around 52.
The original classification identified three families of clouds. These were cirrus (from the Latin of 'hair'—hence wispy, thin clouds), cumulus (meaning a 'heap' or 'pile' for obvious reasons), and stratus (meaning a 'layer' or 'sheet').
This early structuring was done in 1802 by a pharmacist and amateur meteorologist from London, Luke Howard, and picked up by the likes of landscape painter John Constable, who produced reams of cloud studies. Later, in 1896, the clouds were grouped into nine basic forms, each given a number from 1 to 9. This was later revised to include ten cloud forms—1 to 10. But the World Meteorological Organization (WMO), the body responsible for the numbering, later changed the range again to be 0 to 9.
This final change of numbering was for a surprisingly romantic reason. The cloud type with the number 9 (which later briefly became 10) was the cumulonimbus. Although this is classified as a low cloud because its base starts well down, the peaks of a giant cumulonimbus climb higher than any other cloud. If you were perched on top of a cumulonimbus you could consider yourself on top of the world—and this is where the expression 'on cloud 9' comes from. The WMO realized they were being spoilsports turning a cloud 9 into a cloud 10, so they reversed their decision.
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Comments (9)
Thank you for this very interesting and informative article. As a regular flyer myself, and a former student pilot, I would like to suggest adding some more information about what a passenger can see from the vantage point of sitting just behind the wing. I have had lots of fun looking at the control surfaces on the wing -- ailerons, spoilers, flaps -- and using what I see in the deflections of those surfaces, particularly the ailerons to deduce what the pilot is doing.
For example, on a landing approach, from my view out the left window just behind the wing, I see left ailerons deflected downward, indicating that there is a crosswind component from the right, causing the pilot to slip the airplane to the right to correct for the crosswind.
I have also seen pilots using spoilers to slow the airplane to safe turbulence penetration airspeed during straight and level flight, and also once, when there was a steep descent required due to traffic conditions on approach to a very busy international airport. That was a thrilling adventure as the pilot on that flight was also using thrust reversal together with spoilers in order to maintain safe airspeed.
Flaps of course, are quite obvious when landing or taking off.
I know, I have been verbose here, but if I could use some pictures, everything would be much clearer.
Thank you for considering this suggestion.
Posted by Gerard Pereira on February 8,2012 | 04:44 PM
Thrust reversers used in flight? No way, they are interlocked that they can not be used unless the plane is on the ground.
Posted by John Bell on February 12,2012 | 12:31 PM
@John Bell: Yes, many aircraft are certified for in-flight use of thrust reversers. The DC-8 is so certified. However, there are conditions of use which vary aircraft to aircraft...it is unusual!
Posted by Michael Bludworth on February 22,2012 | 05:38 PM
Maybe he meant speed brakes?
Posted by Robb Cole on February 22,2012 | 08:05 PM
When seated in a window seat near the wing leading edge or slightly aft, I have noticed several times the air density change, in certain atmospheric conditions, that allowed a normal shock wave to be visible in the vicinity of the engine nacelle intersection with the wing leading edge on a jet aircraft. This shock wave would be quite stable and proved that the gas dynamic textbook illustrations were accurate. The aircraft itself was not travelling supersonically but the air was being locally accelerated enough to approach or exceed sonic conditions.
Posted by Tom Lisec on February 23,2012 | 09:05 PM
Thanks for the snippet of information. Keep up the good work. My personal joy in flying is land use and geography / geology. Saw my first wind farm a year ago (Minnesota) and it took me a while to recognise the site and its minimal impact.
Posted by ErnestPayne on February 24,2012 | 08:26 AM
Was that steep approach into Washington National by chance? They tend to name it after the basic tool we know as the crowbar. I rode it in a USAIR Dc-9 once. Quite a ride, but I'm pretty sure he didn't use any reverse.
Posted by Markus on February 27,2012 | 11:53 AM
Would a runway facing due North be numbered 36 or 01?
Posted by Dave R. on February 28,2012 | 08:50 PM
A runway facing north is numbered 36. Approach it from the opposite end and it's numbered 18.
Posted by Auntie Analogue on March 23,2013 | 12:14 AM