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 Post subject: Re: Meteorological Weather Quiz (OQ)
Unread postPosted: Mon Mar 30, 2009 5:48 am 
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Maybe so OWN, but that was a spot on response.

Ok, if a strong wind is blowing and you are coming in to land in an aircraft, you will frequently feel the plane drop even though there has been no previous bumps. This is caused by a specific weather phenomena. Any ideas?

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 Post subject: Re: Meteorological Weather Quiz (OQ)
Unread postPosted: Mon Mar 30, 2009 6:01 am 
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:hmz: Oh, so you're a real pilot too!
Okay, to the question at hand ... :hmz: :hmz:

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 Post subject: Re: Meteorological Weather Quiz (OQ)
Unread postPosted: Mon Mar 30, 2009 6:15 am 
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Excellent question, TP! I don't really know, but I suppose it must be due to something about the aircraft creating some kind of low pressure under it as it descends, which allows the greater pressure above it to force it downwards??

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 Post subject: Re: Meteorological Weather Quiz (OQ)
Unread postPosted: Mon Mar 30, 2009 6:42 am 
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Nope OWN, this is created simply by something the weather is doing :wink:

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 Post subject: Re: Meteorological Weather Quiz (OQ)
Unread postPosted: Tue Mar 31, 2009 11:03 pm 
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Maybe you are flying through a low pressure cell??

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 Post subject: Re: Meteorological Weather Quiz (OQ)
Unread postPosted: Wed Apr 01, 2009 1:11 am 
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Nope. On review OWN's answer reflects what has happened but there is something in the weather that has caused this.

Anthony, it's not a low pressure cell - you would be up and down with these.

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 Post subject: Re: Meteorological Weather Quiz (OQ)
Unread postPosted: Wed Apr 01, 2009 3:26 pm 
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Air pocket? :D or is that a low pressure cell??? :redface:

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 Post subject: Re: Meteorological Weather Quiz (OQ)
Unread postPosted: Thu Apr 02, 2009 2:26 am 
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Quote:
Air pocket? or is that a low pressure cell???


Nope - a cell would be considerably larger than a air pocket :wink: Seriously though, an air pocket is a downward moving stream of air which could have been the answer, but in this case it is not what I was looking for.

I'm sure we could run to or three questions at a time on this type of quiz? :hmz:

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 Post subject: Re: Meteorological Weather Quiz (OQ)
Unread postPosted: Tue Apr 07, 2009 3:09 am 
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I don't think running more than one question at one time is a good idea, Timepilot. Some questions would be neglected and we would lose track of what was answered or not answered. Let's keep it one question at a time, although once the correct answer is given, and validated by the question poser, anyone else can ask any question they wish (to do with weather, of course!)

I'm still baffled. :wall: Great question though! So it is something that creates a downdraft then? :hmz:
Approaching thunderstorm, maybe?

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 Post subject: Re: Meteorological Weather Quiz (OQ)
Unread postPosted: Tue Apr 07, 2009 3:42 am 
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No problem OWN - just a thought :)

Okay, how to respond........ :hmz:

The downward movement is in the aircraft, but the phenomon is not downward.

Consider how an aircraft stays in the air and what could cause an aircraft to "sink"

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 Post subject: Re: Meteorological Weather Quiz (OQ)
Unread postPosted: Tue Apr 07, 2009 3:50 am 
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The wing causes a lower pressure above it than below it, hence the aircraft is forced upwards. So it must have something to so with the variation of this pressure. :hmz:
If something increased the pressure above the wing, this would force the aircraft downwards; or, conversely, if something decreased the pressure below the wing.
Now what? :hmz: :hmz:

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 Post subject: Re: Meteorological Weather Quiz (OQ)
Unread postPosted: Tue Apr 07, 2009 4:07 am 
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OWN, your very much on the right track. I worded the question to try and give some clues - happens regularly at our general aviation field here in Perth

The last part of your previous answer is one of the potential causes of this phenomenom - think about the "shape" of an approaching thunderstorm and it's horizontal components.

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 Post subject: Re: Meteorological Weather Quiz (OQ)
Unread postPosted: Tue Apr 07, 2009 5:06 am 
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I know I'm groping here, and not doing much justice to the excellent question, but as no-one else is saying a word, I'll keep going:

A thunderstorm has a thunderhead with downdrafts, and lightning bolts that create sudden pressure changes.

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 Post subject: Re: Meteorological Weather Quiz (OQ)
Unread postPosted: Tue Apr 07, 2009 5:23 am 
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OWN, again, your deductive process is working well. As with the "I'm thinking of..." quiz, I'm afraid I'm going to have to bail. For the next coulpe of days I'll be able to look but can't post as I'm flat out with a bit of a crisis at work. :(

So, in all fairness to keep the quiz going, I'll supply the answer and let another question be posed.

The phenomina that I was talking about is wind shear. Wind shear, in the scenario posted, is a difference in horizontal wind velocity at different altitudes. An aircraft coming into land aims for a set airspeed. At say 300 foot the wind may be blowing directly into the aircraft at 20 knots, the aircraft flies through 200 feet, but the wind speed has dropped to 10 knots causing the aircraft to sink (quite dramatically) because of the sudden loss of lift under the wing generated by the wind. Flying a light aircraft in these situations calls for some significant throttle movements to maintain altitude.

Again, sorry OWN, you were doing a sterling job. :thumbs_up:

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 Post subject: Re: Meteorological Weather Quiz (OQ)
Unread postPosted: Tue Apr 07, 2009 5:34 am 
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Okkaaaayyyyy; Wind Shear; I've heard of that, but have never had the pleasure to pilot a craft through it. Sounds pretty dangerous - I suppose some planes can plough into the ground if they're not careful? How drastic can the drop be?

(Sorry you're all tied up at work.)

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