met help needed

[bassamhadad]

hi all happy pilots , i need some help with met , this question is :-


if you fly at right angels to a jet streams in Europe with a decreasing outside air temprature, you will experience?


1- decreasing groundspeed

2- increasing groundspeed

3- starboard drift

4- port drift

[peb]

I think that is starboard drift.

:ok:

[OneIn60rule]

Jet streams are related to cold/warm fronts. You cannot per say have a front without a Jet stream. This question tries to make it more complicated by saying that you cross a jet stream at right angles instead of just saying that you are going through a cold front.

A cold front is a HIGH pressure area. High pressure has clockwise movement. If you draw a picture of a HIGH and a plane flying through it you can tell which way the wind will blow you.
I'm not a 100% sure but it would seem to me that you'd be blown to the left (port).

I might be wrong and you might actually be going over a Warm front. In that case the answer would change to starboard drift.

Sorry.

[BillieBob]

In broad terms, the jetstream over Europe flows from west to east and temperature decreases towards the North pole. As an aircraft crosses the jetstream heading north, it will drift to the east - i.e. to starboard.

What kind of sick mind thinks up these ridiculous and totally irrelevant questions?

[Electric Sky]

Jetstreams are found between airmasses of different temperatures, one side of the jet being warmer than the other. Rule to remember is that in the northern hemisphere, with your back to the jetstream the cold air is on your left (opposite in SH). Applying this theory to the question you will see that the jetstream must be coming from the left, as all jetstreams found in Europe are westerly.

Hope this helps.

ES ;)

[bassamhadad]

thank you everybody for helping me , i can say that the right answer is ( port drift ) and this is a JAA question .

[peb]

I think that this is the question that you mean:

While crossing a jetstream at right angles in Western Europe (3000 FT below its core) and OAT is decreasing, what would be the prevailing wind?

A)Crosswind from the right
B)A headwind.
C)A tailwind.
D)Crosswind from the left

The right answer would be D for sure.
In you question would be starboard drift.



Here you have an other example:

An aircraft over Western Europe is crossing a jet stream 2500 FT below its core at right angles. While crossing, the outside temperature is increasing. The prevailing wind is:

A)tailwind.
B)headwind.
C)from the right
D)from the left.

The right answer would be C

I hope that this helps


:ok:

[Mass Times Velocity]

Bass

I'd double check that JAA answer if I were you, the wind will be coming from your left which means that your port side would be getting pushed and that would give you starboard drift, have a word with your groundschool, a lot of the JAA questions are very loosely worded and depending on someones interpretation there can be more than one correct answer!

MTV:{

[no sponsor]

I would say starboard drift:

If you are moving to an area of decreasing temperature, then you must be moving from an area of warm air to cold, i.e. you are passing through the warm front. The jet stream would be blowing north/south, therefore if you were heading east, you would be pushed south, i.e. to Starboard. If heading west, to port.

Actually come to think of it, there's no way you would know, so perhaps it is that your groundspeed would increase...

[Send Clowns]

One in Sixty, I have to point out a misconception in your answer that is rather alarming if you have not passed met yet.

A cold front is not in a high pressure area! In fact active fronts are all associated with depressions. The upmoving air of the low pressure region is what allows thick cloud banks to form. The situation with a jetstream also certainly does not change between cold and warm fronts. Going from high temperature to low the aircraft is passing from the warm sector to the cold, and in the northern hemisphere the frontal jetstream, which is just underneath the warm-sector tropopause in the warm sector, close to the front, blows with the cold sector to its left. Therefore if you are crossing to the cold sector the jet is blowing from the left.

Remember that the definition of a front as warm or cold is determined only by the direction of movement of the airmasses at their surface expression, not by the jet across the airmass.

If you need a diagram of this description and can't find the appropriate one in your own books then send me an email address and I will try to get you something from our manual.

Oh, and don't quote me on it, it's not my subject, but I believe you can have a (weak) front without a jetstream. Jetstreams must be moving at greater than 60 kts, and while there will always be a similar wind aloft it may not be fast enough for the definition.

Send Clowns
General Navigation Instructor
BCFT

P.S. Everyone else is correct, except the alleged JAA answer. The drift is to starboard.

[OneIn60rule]

I can see where I went wrong.

[Send Clowns]

Good :D Want you guys to pass as quickly as possible and get onto the fun bit ;)

[pugzi]

Wow, some serious and wierd ideas floating round here.
I'll help clarify, I hope.
Ok. winds are created by variations in pressure. Air would like to rush into low pressure areas, but alas, in the northern hemisphere the air is turned to the right. Thus the rule, BACK TO THE WIND LOW ON YOUR LEFT.
BUT, Upper winds are a little different, the pressure upstairs is determined by temperature downstairs. Cold air makes pressure fall very rapidly with altitude, so therefore a lower pressure than normal would be found upstairs. Warm air does the reverse and creates higher pressures in the upper atmosphere.
So, the upper wind rule is BACK TO WIND COLD ON YOUR LEFT (because it's the old air making the low pressure in the first place).

Lets say there is a massive temperature variation downstairs on the surface of the earth, then there would be a massive pressure variation in the upper atmosphere and this would result in a whopper wind!!!. An upper wind >60kts is a jetstream.

Now, a "front" is a boundary between airmasses of different temperatures. So whenever you have a front, you will have a big pressure difference in the upper atmosphere. The stronger the front, the stronger the pressure variation upstairs and the stronger the wind.

Weak fronts, weak upper wind et etc

Phew, bit much after easter, but hope it helps. Or just buy my cd (hey hey)

Steve