Jet Streams

[Disney fan]

Can anyone explain Jet Streams to me.. Why are they common over the Atlantic and why are they more prevalent in the winter???? ( Sorry if I sound a bit stupid)

Lynda

[spleisher]

Lynda... coopied this from an internet site.. see if this helps...

"The jet stream is a current of fast moving air found in the upper levels of the atmosphere. This rapid current is typically thousands of kilometers long, a few hundred kilometers wide, and only a few kilometers thick. Jet streams are usually found somewhere between 10-15 km (6-9 miles) above the earth's surface. The position of this upper-level jet stream denotes the location of the strongest SURFACE temperature contrast"


From the perseoctive of a pilot, it is important to know where the Jetstream is and what it is doing from a standpoint of flight planning. Time enroute is always calculated based on a number of factors. WInd and weather are a couple of those factors. If you are flying into the Jetstream, your time enroute will be increased. If you have it at your tail, you will get where you are going faster.

The jetstream is often sometimes associated with CAT, or Clear Air Turbulence. It is therefore also importand to know how you will be flying in relation to the Jetstream from a standpoint of how comfortable the flight is likely to be.

Ray or Bob, you guys may be able to chime in and provide more detailed and relevant information on this than I can. I generally stay below FL20, so I really don't have a lot of experience first-hand with the Jetstream.

Hope this helps!
Scott

[MarcoAviator]

I'll try to explain as best as I can ... without falling into Jargon.

The atmosphere is heated unevenly. It's cold at the north pole and it's hot at the equator.

Incredibly air doesn't mix up. Two air blobs of different temperature can touch but stay independent and isolated for some time without mixing with each other at all (you would think that hot air and cold air, touching each other would make a blob of ... warm-luke air ... but no).

These air blobs have different density. Similar to oil and water... they don't mix even if you pour them in a glass.

Cold air is dense and compacted. Hot air is thin and expanded.

So the cold air over the North pole is denser and it doesn't expand as much to space as the hot air over the equator does (in other words, the atmosphere is not equally thick all over earth, it's "taller" over the equator and "shorter" over the poles).

It's like the earth is "squished" at the poles.

Only difference is that the boundary between the cold air at the north and the warm air at the south (in our emisphere) is not smooth. It breaks.

the area where there's this "drop" in atmosphere height creates a small horizontal "cyclone" of air ... kinda like a wide, slow moving, sleepy pipe of air, laying on its side. It's not a real cyclone ... it's just a mass of air sitting there in the upper atmosphere, circling.

This is also why the jetstream is located near areas of temperature difference: that's where the two layers of air are meeting.

This "cyclone" (because of the rotation of the earth) moves (from west to east if I remember correctly).

That's the Jet stream. It's always there. It's just that in the summer it's way up north, and in the winter it descends (with the cold air) down south where we are, as the cold blanket of air above the north pole expands.

Sometimes the jetstream can get powerful enough to descend to below normal levels and affect all altitudes of flight.

I really hope I got it right. I am going off my memory here and I am not a meterologist ... just a pilot fascinated by weather.

Take this explanation at face value please: I may be wrong, so the super-duper pilots here with more years of experience of me might need to correct me.

[Disney fan]

Thank you,

Great explanations!

Lynda:)

[CaptainStark]

Flew PHX to St Louis today and the jet was blowing 120KTS from the southwest. Yesterday across the Sierras, it was stronger. Bumpy ride all the way. Slow going westbound. No problem just annoying.

Ray:ray

[EditorASC]

Some additional information, with side links, at:

www.free-definition.com/Jet-stream.html (http://www.free-definition.com/Jet-stream.html)

[EditorASC]

First known human use of the Jet Stream:

encyclopedia.thefreedicti...%20balloon (http://encyclopedia.thefreedictionary.com/fire%20balloon)