Help me with a SAMRA question!!!

[shylnj26]

Hello,

I really don't get this question.. please help me with this question.. Thank you in advance.


Q. If the temperatures to the southeast today are warmer than those to the northwest, the winds aloft would be blowing from the... (recall Buys-Ballot's Law - with your back to the wind, your left hand will point to the area of the lower pressure; for upper level winds, your left hand will point to area of lower temperatures...)

Answer is Southwest, but I do not understand how Southwest become the answer..

[455tt]

The key to this question is the Temperature.

We know that a HIGH has descending air, AKA Subsidence, and the temperature increases.

We also know that a LOW has ascending air, AKA Ascendance, and the temperature decreases.

Therefore, in this example, we will have a LOW to the NW, and a HIGH to the SE. Sketch these in. Since the LOW circulates Counter-Clockwise, and the HIGH circulates Clockwise, at the point the circulation from each system meet, given that wind flows parallel to the isobars/contours, the winds must be from the SW.

You don't need Buy-Ballot's law to solve this question.

[TeePeeCreeper]

The key to this question is the Temperature.

We know that a HIGH has descending air, AKA Subsidence, and the temperature increases.

We also know that a LOW has ascending air, AKA Ascendance, and the temperature decreases.

Therefore, in this example, we will have a LOW to the NW, and a HIGH to the SE. Sketch these in. Since the LOW circulates Counter-Clockwise, and the HIGH circulates Clockwise, at the point the circulation from each system meet, given that wind flows parallel to the isobars/contours, the winds must be from the SW.

You don't need Buy-Ballot's law to solve this question.

^ Outstanding!

[pelmet]

It is just a general question about this law that in my mind has no use to me in the real world( but perhaps it is of some use to some people). The high is to the southeast and the low is to the northwest. Why is this. It appears in theory that the reason that 455tt gave is why(although in my mind, the Arctic highs in the winter give colder air). Air is supposed to flow directly from high to low if the earth were not spinning so use the law to stand with your back to the high pressure system and stick out your left arm. That is pointing southwest.

I suspect that this technique is not used in reality by any pilot and has no use. But, people can feel free to let me know if they have ever used it.

[shylnj26]

The key to this question is the Temperature.

We know that a HIGH has descending air, AKA Subsidence, and the temperature increases.

We also know that a LOW has ascending air, AKA Ascendance, and the temperature decreases.

Therefore, in this example, we will have a LOW to the NW, and a HIGH to the SE. Sketch these in. Since the LOW circulates Counter-Clockwise, and the HIGH circulates Clockwise, at the point the circulation from each system meet, given that wind flows parallel to the isobars/contours, the winds must be from the SW.

You don't need Buy-Ballot's law to solve this question.

Wow.. Thank you so much for your detailed but easy explanation!!!!

[Reinhard]

Air is supposed to flow directly from high to low if the earth were not spinning so use the law to stand with your back to the high pressure system and stick out your left arm.

Buys Ballot's law is a mnemonic to help remember the effect of Coriolis effect on wind.

The law says to stand with your back to the wind, not high pressure system, and the low pressure will be on your left.

[pelmet]

Air is supposed to flow directly from high to low if the earth were not spinning so use the law to stand with your back to the high pressure system and stick out your left arm.

Buys Ballot's law is a mnemonic to help remember the effect of Coriolis effect on wind.

The law says to stand with your back to the wind, not high pressure system, and the low pressure will be on your left.

Thanks, I did get the correct answer but it may have just been sheer luck.

Once again, has anybody ever used the stand with your back to the wind to glean any useful weather information about enroute weather, other than takeoff/landing direction(which one does not need knowledge of this law to figure out). I have this feeling that no pilot is getting any useful real world benefit from being able to answer this question.

[Roar]

Air is supposed to flow directly from high to low if the earth were not spinning so use the law to stand with your back to the high pressure system and stick out your left arm.

Buys Ballot's law is a mnemonic to help remember the effect of Coriolis effect on wind.

The law says to stand with your back to the wind, not high pressure system, and the low pressure will be on your left.

Thanks, I did get the correct answer but it may have just been sheer luck.

Once again, has anybody ever used the stand with your back to the wind to glean any useful weather information about enroute weather, other than takeoff/landing direction(which one does not need knowledge of this law to figure out). I have this feeling that no pilot is getting any useful real world benefit from being able to answer this question.

So true! I remember on mine there was 6 questions on complex lows. Not once have I ever had a need to know that in real world ops.

[Nauclerus]

I don't get it ? Here are 4 points A, B, C, D, where at each point "the temperatures to the southeast today are warmer than those to the northwest". The wind direction is from the north at A, from the west at B, from south at C, and from the east at D.

[pelmet]

Not quite sure I understand your point but I think there can be a big difference between the theoretical world and the real world. A lot of people don't understand this.