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Faro
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Jet Streams / Frontal Systems / Rossby Waves

Mon Dec 20, 2010 12:21 pm

What is the relationship between jet streams, the position of frontal systems and Rossby waves:

- Are Rossby waves another name for jet streams?
- Are hot/cold fronts co-located with the position/layout of jet streams?
- What is the relationship between jet streams (which are high altitude phenomenon) and frontal systems (which are low altitude phenomenon)? How can they influence each other if they occur at significantly different altitudes?
- How far south can jet streams occur?

Faro
The chalice not my son
 
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glen
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RE: Jet Streams / Frontal Systems / Rossby Waves

Mon Dec 20, 2010 4:32 pm

Quoting faro (Thread starter):
Are hot/cold fronts co-located with the position/layout of jet streams?

  

Quoting faro (Thread starter):
- What is the relationship between jet streams (which are high altitude phenomenon) and frontal systems (which are low altitude phenomenon)? How can they influence each other if they occur at significantly different altitudes?

Frontal systems are not a low altitude phenomenon. A front is the layer between cold and warm air-masses and reaches up to the tropopause (the upper limit of the troposphere). Its direction of movement defines whether it's a cold- or warm-front. (Cold air moving towards warmer air = cold front and v.v.)
Because colder air is more compressed, levels with the same pressure are at lower altitudes than in warmer air. Therefore at a given altitude you have lower pressure on the cold side of the front than on the warm side. This pressure gradient is increasing with altitude, being the greatest just below the tropopause. This big pressure difference creates a strong wind. Due to the Coriolis-effect (rotation of the earth) this wind is not blowing from the warmer air to the colder but gets deflected and is blowing parallel to the frontal system: this is the jetstream.

Quoting faro (Thread starter):
- How far south can jet streams occur?

There are mainly two jetstream-systems: The polar jet between the (cold) polar air and (warm) tropical air and the subtropical jet between tropical and equatorial air (tropical air being "colder" than equatorial air). The polar jet lies between 30° and 60° latitude; closer to the equator during winter time. Having the same systems on northern and southern hemisphere you find the southern polar jet up to 60°S.

Quoting faro (Thread starter):
- Are Rossby waves another name for jet streams?

No, but they are related. The frontal systems and therefore the jetstreams are not straight around the earth. Due to the influence of high and low pressure areas the front gets bended and have a meander-like shape around the globe. These meanders can also be seen as waves and are sometimes called Rossby waves because their mathematical description is called so.
"The horizon of many people is a circle with zero radius which they call their point of view." - Albert Einstein
 
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Faro
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RE: Jet Streams / Frontal Systems / Rossby Waves

Mon Dec 20, 2010 11:57 pm

Quoting glen (Reply 1):
Reply 1

Thanx for the detailed reply, much obliged.

Faro
The chalice not my son
 
soon7x7
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RE: Jet Streams / Frontal Systems / Rossby Waves

Tue Dec 21, 2010 12:11 am

Quoting faro (Thread starter):
Are Rossby waves another name for jet streams?

In 38 years...you are the first person I have ever heard use the title, "rossby waves"...with all the weather channels we have and all the storm stories...I have never heard anyone use the term 'cept myself. Welcome to the club of two!...actually 3 since "Glen" apparently has knowledge of them as well.
 
411A
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RE: Jet Streams / Frontal Systems / Rossby Waves

Wed Dec 22, 2010 1:19 am

Quoting soon7x7 (Reply 3):
In 38 years...you are the first person I have ever heard use the title, "rossby waves"...

The term was used by the met folks during WWII, for ops over Japan.
IE: much older than you might imagine.
 
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Faro
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RE: Jet Streams / Frontal Systems / Rossby Waves

Wed Dec 22, 2010 12:01 pm

Quoting 411A (Reply 4):
Quoting soon7x7 (Reply 3):
In 38 years...you are the first person I have ever heard use the title, "rossby waves"...

The term was used by the met folks during WWII, for ops over Japan.
IE: much older than you might imagine.

I came across the term in my climatology textbook but it was not at all clear whether Rossby waves are themselves jetstreams or parts of jetstreams or even something else. I guess they are more a perceived pattern of jetstream juxtaposition than real, climatological phenomenon in their own right. But then these two are conceptually difficult to fully separate, akin to distinguishing the dancer from the dance.

Faro
The chalice not my son
 
kiwiflyer1
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RE: Jet Streams / Frontal Systems / Rossby Waves

Thu Dec 23, 2010 11:55 am

Faro, as far as I understand the Rossby Waves are the waves found in the general high level mid-lattitude airflow, within that high level airflow you will find the jet streams (areas with the highest windspeed).

If you look at the wind pattern in the link below you can see a wide area of airflow making a wave from the bottom of Greenland, down to Spain, then up to Russia.

http://ows.public.sembach.af.mil/ind...-GLOBAL_WIND-TEMP_FL300_24_00Z.png

Then compare this with the jet streams of the same time, they only show up in the fastest parts of the wave from the previous example. (The jet streams are the thick black lines incase you've never seen these charts before, also its shown in a very different projection than the first so just compare with the landmasses.)

http://weather.noaa.gov/pub/fax/PGDE14.PNG

Hopefully those links are still current by the time you see them.
 
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Faro
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RE: Jet Streams / Frontal Systems / Rossby Waves

Thu Dec 23, 2010 11:06 pm

Quoting kiwiflyer1 (Reply 6):
Faro, as far as I understand the Rossby Waves are the waves found in the general high level mid-lattitude airflow, within that high level airflow you will find the jet streams (areas with the highest windspeed).

If you look at the wind pattern in the link below you can see a wide area of airflow making a wave from the bottom of Greenland, down to Spain, then up to Russia.

http://ows.public.sembach.af.mil/ind...-GLOBAL_WIND-TEMP_FL300_24_00Z.png

Then compare this with the jet streams of the same time, they only show up in the fastest parts of the wave from the previous example. (The jet streams are the thick black lines incase you've never seen these charts before, also its shown in a very different projection than the first so just compare with the landmasses.)

http://weather.noaa.gov/pub/fax/PGDE14.PNG

Hopefully those links are still current by the time you see them.

Thanx for the info and links.

Would it be fair to say that Rossby waves are of no practical use to aviation, being a climatological phenomenon rather than a meteorological one? Do they ever show up on met charts of any sort independently/distinctly from individual jetstreams?

Faro
The chalice not my son

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