How do they measure winds aloft?

kicktireslightfires

kicktireslightfires

Pre-takeoff checklist
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kicktireslightfires
I read that it's via a radiosonde suspended underneath a weather balloon, but given the winds aloft data is updated twice a day on Aviation Weather Center, is that to mean that every single airport that is reporting winds aloft is sending up a weather balloon into the sky twice a day every day? That seems unlikely. So how are they getting that data twice a day?
 
I thought they were just forecast. Will keep following this for the real brain trusts.
 
Most, if not all, modern airliners have the ability to determine wind direction and speed. Many also have the ability to transmit data to ground stations. I don’t really know why we cannot have near real time wind information at our fingertips, so to say. The technology is there.
 
Greg Bockelman said:
Most, if not all, modern airliners have the ability to determine wind direction and speed. Many also have the ability to transmit data to ground stations. I don’t really know why we cannot have near real time wind information at our fingertips, so to say. The technology is there.
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Yup. Controllers have been asking pilots “what’s the wind up there” for over 20 years that they use for real time decision making. How much the weather guessers use any PIREP info to ‘forecast’, I dunno.
 
kicktireslightfires said:
I read that it's via a radiosonde suspended underneath a weather balloon, but given the winds aloft data is updated twice a day on Aviation Weather Center, is that to mean that every single airport that is reporting winds aloft is sending up a weather balloon into the sky twice a day every day? That seems unlikely. So how are they getting that data twice a day?
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Winds aloft reporting stations are few and far between. But, forecasting has been pretty good for many decades. I once dead reckoned from Nuuk Greenland to Goose Bay Canada - a very long leg - so winds aloft forecasts were key to success. When we finally were able to receive VOR/DME information we were only 20 miles from our planned position. It was all down the winds aloft forecast. [/Edit - that was 1987]
 
MooneyDriver78 said:
Has anyone ever hit one in flight?
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I have often wondered why, if they get released all the time, I have never seen one while flying. I presume (wild-assed guess) that the balloons are still on their way up when they are in the bug-smasher altitude range, and so spend relatively little time there. I HAVE seen toy mylar balloons. Typically I don't notice them until they go zipping by, scaring the crap out of me. Those seem to find an altitude they like and stay there a while.

Tim
 
timrb said:
I have often wondered why, if they get released all the time, I have never seen one while flying. I presume (wild-assed guess) that the balloons are still on their way up when they are in the bug-smasher altitude range, and so spend relatively little time there. I HAVE seen toy mylar balloons. Typically I don't notice them until they go zipping by, scaring the crap out of me. Those seem to find an altitude they like and stay there a while.

Tim
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MooneyDriver78 said:
Has anyone ever hit one in flight? Seems dangerous since they are released over larger airport with nav aids.
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Had a T-38 report a near miss with one while doing a PAR. We saw it on the scope and my student asked if he should call traffic on it. I thought it was just a few birds and it would disappear shortly. Unfortunately it stay there, the aircraft went right by it and I heard “we almost hit something.” After landed I approached the IP, apologized and asked what he saw. He wasn’t completely sure that he didn’t see a UFO. Asked if he wanted me to file a report and he said no.

Come to find out, Camp Elliot, just east of Miramar has a small weather station that periodically launches silver weather balloons. Not the best place for that kind of activity.
 
I believe much of the data is based on the science of atmospherics. They know the air pressure at the surface, and draw the maps with the isobars as per the ground readings. The distance between the isobars determines wind strength; close together, the winds are strong. Temperature would also play into it, and they use satellite readings to determine upper air temps.

The winds also follow the isobars due to Coriolis force. At the surface, the wind will cut across the isobars at angles up to 30°, toward the low or away from the high. Speed and temp also figure into that, as does terrain (more or less drag, valleys often channeling the flow). The winds move counterclockwise around a low and clockwise around a high, in the northern hemisphere. Opposite in the southern.

That's what I remember from CPL/IFR training almost 30 years ago. Correct me if I'm wrong. It served me well enough and still does, as I check the GFAs to see what the winds are, based on the isobars. If I see the isobars crossing the Rockies, with precip shown on the western slopes, I know we're going to get a chinook and it will warm up nicely in the middle of winter.
 
Silent Reader said:
We can (actual real time wind data in-flight):
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Yeah, I get that. But I meant on the ground for pre-flight preparation. I have the same information on my work planes but it doesn’t do me any good for flight planning.
 
One of my customers makes the reporting units that get launched.
 
I was driving down a country road once, in the Michigan thumb region, when I saw what looked like an orange garbage bag out in a plowed farmer's field. After driving past, something about it stuck in my head, and after driving a few miles I decided to turn around and go back. I found a radiosonde! It had an envelope with it to mail it back, which I did...and unfortunately, I didn't get a picture. I will say, it was small and very light (maybe just a few ounces), so if a plane did hit one, the damage to the plane would be minimal. I found this picture online and it looked just like this:
upload_2021-4-4_8-43-21.png
 
kicktireslightfires said:
I read that it's via a radiosonde suspended underneath a weather balloon, but given the winds aloft data is updated twice a day on Aviation Weather Center, is that to mean that every single airport that is reporting winds aloft is sending up a weather balloon into the sky twice a day every day? That seems unlikely. So how are they getting that data twice a day?
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I am not a meteorologist, but I'll take a swing.

The measurements come from radiosondes, IIRC from under a hundred sites, twice a day. Those and other measurements (satellites, radar, buoys, airliners, etc) are used as inputs to initialize numerical weather models (differential equations). The inputs are probably coarser and dirtier than you'd like, but you go to war with the measurements you have. Running the models forward in time (finding a solution to the equations) happens on a grid, like the atmosphere is minecraft blocks 3km on a side. The winds aloft forecast that you read for a location near you (not necessarily one of the launch sites!) is one such forecast product.
 
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Greg Bockelman said:
Most, if not all, modern airliners have the ability to determine wind direction and speed. Many also have the ability to transmit data to ground stations. I don’t really know why we cannot have near real time wind information at our fingertips, so to say. The technology is there.
Click to expand...
The airlines can't make money from it. You'd think they would send it back to their own HQ so they can ask for routings with better wind to save money on fuel.
 
In my experience winds aloft forecasts in the western Colorado mountains are not very accurate, and I question them everywhere as a result.
I flew over the elk range one day from KEGE to KGUC, winds aloft was predicting 50kts at 15,000 from the west south west, I flew by Capitol Peak at 14,500 on a magic carpet. Smooth as glass ride and no perceptible crabbing due to crosswind. I'd estimate that the wind at 14,500 was 10kts or less. Last fall I went out to do some stalls to see what my ground speed was vs indicated airspeed. Winds aloft reported 2kts at 9000 and 3kts at 12000, I was at 10,000. Airspeed indication going southwest at 40mph gave a ground speed of around 40mph, I turned around and went the other way, 40 indicated was mid 60's ground speed. Clearly not 2kts! I have seen this many times.

Over Nebraska a couple years back, I was at 10,500. I checked the winds aloft forecast on ForeFlight, it indicated that I would have a 10kt advantage at 12,000. So, I climbed to 12,500. My ground speed was actually slightly less up there.
 
kicktireslightfires said:
I read that it's via a radiosonde suspended underneath a weather balloon, but given the winds aloft data is updated twice a day on Aviation Weather Center, is that to mean that every single airport that is reporting winds aloft is sending up a weather balloon into the sky twice a day every day? That seems unlikely. So how are they getting that data twice a day?
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I can tell you isn't every single airport. My airport is listed as a winds aloft site, yet there is no one here launching anything. They must be extrapolating.
 
Cap'n Jack said:
The airlines can't make money from it. You'd think they would send it back to their own HQ so they can ask for routings with better wind to save money on fuel.
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I think was the idea of "free flight" which has taken a back seat to just getting "flight" these days. ATC routings are not particularly flexible.
 
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