Is it colder at the approach end of the runway?

On Apr 2, 5:43 pm, "Capt. Geoffrey Thorpe" The Sea Hawk at wow way
d0t com wrote:
If I were to guess (and it's just a guess) I would suspect that the long
open space along the runway allows the wind to blow a little faster (less
drag from buildings and stuff) and pulls down a little more cool air from
higher altitudes.

A similar sort of guess would be that it's the same effect as a sea
breeze. The runway surface heats up and causes a cool breeze towards
it.

Chris, is this in the morning or afternoon?

Kev

re spending money to figure that out. I thought that was common
knowledge.

Well, sometimes things that are common knowledge are incorrect.

Jose

Jose, you sound like your buddy MX. When I returned from luch today I
walked
from a concrete parking lot over about 10 feet of grass to enter the
building. I did not need airborne equipment to tell me it was warmer
over
the concrete than it was over the grass.

Well, yeah, but I wouldn't use that to make the decision as to whether
or not huge piles of money should be spent to combat global warming.

I think we need something from traceable, calibrated instruments with
error bars on the numbers, which is what hopefully the airplane is
getting.

--
Jim Pennino

Just to add a little more "food for thought" to the Global Warming issue: I
recently heard another of those poorly attributed sotries on radio. In this
case, it seems that some of the Siberian reporting stations were
abandonned--so the subsequent data was merely compiled without them...

As to the original question, I presume that the road near the approach end
of the runway is simply in a less built-up area that the rest of Chris'
Dad's morning commute. That would be nothing new; there has been a very
noticeable change of temperature in less than a quarter mile--in that type
of transition--for as long as I can remember. With the windows open, you
can suddenly wonder if you should have brought a jacket...

Peter

I would sooner think that it is the ground in the area... is there water or
a marshy area near there?

BT

"Chris W" wrote in message
...
My dad drives along the south side of OKC to work every day and his OAT in
his car always goes a few degrees colder around the where the extended
centerline for the runways would intersect the road. Then it goes right
back up after he is through that area. He thinks this is because the
airplanes are descending from very cold air and bringing down some of it
with them. He has noted that this isn't always the case but it often is.
You would think most of the traffic would be landing from the north since
our winds are mostly from the south, but it seems like I see a lot of
traffic coming in from the south, maybe because it is easier for the
traffic from DFW to just come strait in.

Anyway, any one here think it is really the case that the planes are
causing the temperature to be lower on the approach end of the runway? I
guess if he monitored the ATIS frequency to find out which runway was
active when he drives by every day, he would have a better idea.


--
Chris W
KE5GIX

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Is it colder at the approach end of a runway?

No.


--

Tony Roberts
PP-ASEL
VFR OTT
Night
Cessna 172H C-GICE

tony roberts wrote:
Is it colder at the approach end of a runway?

No.

But isn't it true, or so I've been told, that it is always cloudier over an
airport than the surrounding area? :-)

Robert M. Gary wrote:

I live near Sacramento where we have long periods of 100+ degree
temps. The gov't has been doing research here on the affect of asphalt
and roofs (not sure why) on temps. They fly a plane overhead in the
afternoon with sensitive heat detecting equipment. They seem to
believe the city is much hotter simply because of the pavement and the
roofs.


Don't know why they'd be studying it in Sacramento. Here in Phoenix it has
long been known as the "Heat Island". Basically, asphalt, roofs and concrete
absorb much more heat than dirt or grass. The result is that this excess
heat is liberated slowly after the sun goes down and raises the overnight low
temperature in populated areas.

If you live in a rapidly expanding desert town long enough, it's easy to
see. When I moved here, there were about 1.5 million people in the metro
area. During the hottest part of the summer, overnight low temperatures
stayed in the mid to upper 80s. Nowadays, we have about 4 million people and
the overnight lows stay in the low to mid 90s at the peak of summer. Daytime
temperatures haven't shown any corresponding increase.

John Galban=====N4BQ (PA28-180)

--
Message posted via AviationKB.com
http://www.aviationkb.com/Uwe/Forums...ation/200704/1

On Apr 2, 5:33 pm, "Vaughn Simon"
wrote:
"Marco Leon" wrote in message

...

Air does not "stick" to an airframe enough to change the ambient temperature
of a given area no matter how small.

No, but everyone who has ever studied for their Private written knows that
the wake of an aircraft is accelerated down. So the passage of an aircraft
would cause a very temporary downward flow of air. Would the effect be enough
to noticeably change local temperatures? I doubt it; but who the hell am I?

What time of day does he go by? I could see the downwash mixing up
the air, and if there is a hot surface layer this could cool it.

As an example of downwash changing the temperature, I have heard
helicopter pilot stories about 'frost flights' at strawberry farms.
The task is to spend the night at the farm, and if the frost alarm
goes off in the wee hours you have to fly low over the fields in the
dark until the air is stirred up and the frost danger goes away. It
apparently is very effective in preventing frost damaged berries.

John Halpenny

Is it colder at the approach end of a runway?

No.

But isn't it true, or so I've been told, that it is always cloudier over an
airport than the surrounding area? :-)


Now that IS true

Tony

--

Tony Roberts
PP-ASEL
VFR OTT
Night
Cessna 172H C-GICE

On Apr 2, 9:18 pm, "John Halpenny" wrote:
On Apr 2, 5:33 pm, "Vaughn Simon"
wrote:

"Marco Leon" wrote in message

m...

Air does not "stick" to an airframe enough to change the ambient temperature
of a given area no matter how small.

No, but everyone who has ever studied for their Private written knows that
the wake of an aircraft is accelerated down. So the passage of an aircraft
would cause a very temporary downward flow of air. Would the effect be enough
to noticeably change local temperatures? I doubt it; but who the hell am I?

What time of day does he go by? I could see the downwash mixing up
the air, and if there is a hot surface layer this could cool it.

As an example of downwash changing the temperature, I have heard
helicopter pilot stories about 'frost flights' at strawberry farms.
The task is to spend the night at the farm, and if the frost alarm
goes off in the wee hours you have to fly low over the fields in the
dark until the air is stirred up and the frost danger goes away. It
apparently is very effective in preventing frost damaged berries.

John Halpenny


This has been done with fixed-wing airplanes, too. An airliner
on approach can't help but drive down air from a couple hundred feet
up. Problem with that, of course, is that the OP says his dad notices
this on the drive to work, presumably in the morning, and the air
aloft will be warmer rather than colder at that time. The nocturnal
inversion is still in play in the morning, before the surface heats
up. It's that warmer air the helicopters or other craft are driving
down at night into the orchards or vineyards or citrus groves.

Dan

I posted this and then got busy so I am just now reading the replies. I
will try to respond to most of the replies in this message.

Airport is KOKC (Will Rogers International)
The location where the temperature change is noticed is SW 104th Street
which is just a hair over 1 mile south of the runway 35L and 35R.

We weren't thinking so much that the temperature change was due to the
down wash of air following the plane as it was the fact that at 30,000
feet the plane mass (which is quite a bit in an airliner) becomes very
cold and as it moves through the warmer air at the the lower altitudes
near the airport, it absorbs the heat from the air and therefore leaves
it colder than it was.

I do suspect though that as at least one poster suggested it may be due
to the fact that there isn't much development out there. If you look at
the satellite map, you will see very little development for a long way
south.

Another reason my dad thought this might be at least partially caused by
the aircraft is the fact that sometimes it is warmer there. In that
case he was thinking that the planes had been sitting on the ground for
some time and most of the structure was at least as warm as the ambient
air, then with the engines putting out full power for about 3 miles
before they cross the road, would be generating a lot of heat. So if the
planes were departing on runway 17L or 17R, it wold tend to warm it up.

However it could just be due to what direction the wind was blowing.
South wind blowing over mostly farm land and the river a few miles
south. Keeping it cool and a north wind blowing over the city, keeping
it warmer.


--
Chris W
KE5GIX

"Protect your digital freedom and privacy, eliminate DRM,
learn more at http://www.defectivebydesign.org/what_is_drm"

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