Decent into Cleveland

[john cop]

Have been inactive for many years.

About 20 years ago, when flying up from the south, I got suckered in.
The tops slowly rose untill I was flying at over 15,000 (Mooney 201)
near Cleveland, It was clear on top and the temp was in the mid 40s
on the ground, and the freezing level was high enough so I wasn't
worried.

When cleared for decent, ice formed at an incredible rate - must have
picked up over an inch of rime in seconds near the tops. Once below
the sun heated top layer, the accumulation virtually quit. Breaking
out below at about 4,000, the temp was already well above freezing,
but no ice was dissapearing.

While being vectored into the approach, I ran some test to make sure
the plane was behaving normally and was capable of climbing. On hind
site, I should have refused the approach clearance and waited for the
ice to fall off.

Anyhow, after having read accounts about people stalling on final and
etc., I brought her in about 20 knots fast over the numbers and
chopped everything. I damn near overran a 5,000 ft. runway - the
sucker didn't want to land.

Rime ice, I have since found, can lower the stall speed (raises the
dragg). It increases the leading edge of the wing. This was verified
by test I did for a senior project in a wind tunnel using an airfoil,
rubber cement, and sugar. The Reynolds number was way off for that
test, so it could be suspect. However, I had occassion to take to one
of the crew of the icing planes over at NASA who confirmed all this
and it sure would account for my landing problem above.

Anyhow, after parking the plane, ice was still falling off in big
chunks for 10 or 15 min.

[Bob Gardner]

I question the "sun-heated" part of your post. The sun heats the earth,
which in turn heats the atmosphere from the bottom up. Most ice is found in
the top one-third of any cloud. It does take a while for ice to sublimate
off...I have picked up ice climbing through a layer out of Seattle that
didn't disappear for about 30 minutes, and this was in a Baron.

Glad that it worked out, though.

Bob Gardner


"john cop" > wrote in message
om...
> Have been inactive for many years.
>
> About 20 years ago, when flying up from the south, I got suckered in.
> The tops slowly rose untill I was flying at over 15,000 (Mooney 201)
> near Cleveland, It was clear on top and the temp was in the mid 40s
> on the ground, and the freezing level was high enough so I wasn't
> worried.
>
> When cleared for decent, ice formed at an incredible rate - must have
> picked up over an inch of rime in seconds near the tops. Once below
> the sun heated top layer, the accumulation virtually quit. Breaking
> out below at about 4,000, the temp was already well above freezing,
> but no ice was dissapearing.
>
> While being vectored into the approach, I ran some test to make sure
> the plane was behaving normally and was capable of climbing. On hind
> site, I should have refused the approach clearance and waited for the
> ice to fall off.
>
> Anyhow, after having read accounts about people stalling on final and
> etc., I brought her in about 20 knots fast over the numbers and
> chopped everything. I damn near overran a 5,000 ft. runway - the
> sucker didn't want to land.
>
> Rime ice, I have since found, can lower the stall speed (raises the
> dragg). It increases the leading edge of the wing. This was verified
> by test I did for a senior project in a wind tunnel using an airfoil,
> rubber cement, and sugar. The Reynolds number was way off for that
> test, so it could be suspect. However, I had occassion to take to one
> of the crew of the icing planes over at NASA who confirmed all this
> and it sure would account for my landing problem above.
>
> Anyhow, after parking the plane, ice was still falling off in big
> chunks for 10 or 15 min.

[karl gruber]

*****didn't disappear for about 30 minutes, and this was in a Baron.****


I thought we were in a Bonanza!

Best,
Karl

[john cop]

"Bob Gardner" > wrote in message >...
> I question the "sun-heated" part of your post. The sun heats the earth,
> which in turn heats the atmosphere from the bottom up. Most ice is found in
> the top one-third of any cloud.

I don't think this works with a heavy cloud deck and clear on top
where you get little sun penetration. I would think there would have
to be a warmer boundry layer at the tops. This would certainly
account for the much heavier concentration of super cooled moisture.
There was no question the really heavy icing was right at the tops -
you could hear the stuff applying itstelf.


It does take a while for ice to sublimate
> off...I have picked up ice climbing through a layer out of Seattle that
> didn't disappear for about 30 minutes, and this was in a Baron.

Sumblimate, yes, but I expected the stuff to fall off pretty quickly
once the temp was well above freezing. It didn't - probably took a
long time to warm the plane up.

>
> Glad that it worked out, though.
>

Me too.

[karl gruber]

I would suspect your OAT to be incorrect.

Ice invariably will melt off fast, and in big chunks, below the freezing
level.

Karl

[Bob Gardner]

Different trip.

Bob

"karl gruber" > wrote in message
...
> *****didn't disappear for about 30 minutes, and this was in a Baron.****
>
>
> I thought we were in a Bonanza!
>
> Best,
> Karl
>
>

[Bob Gardner]

Look at any text on the atmosphere and you will learn that temperature
decreases with altitude, cloud cover not withstanding (absent an inversion).
The sun does not heat clouds.

Bob Gardner

"john cop" > wrote in message
om...
> "Bob Gardner" > wrote in message
>...
> > I question the "sun-heated" part of your post. The sun heats the earth,
> > which in turn heats the atmosphere from the bottom up. Most ice is found
in
> > the top one-third of any cloud.
>
> I don't think this works with a heavy cloud deck and clear on top
> where you get little sun penetration. I would think there would have
> to be a warmer boundry layer at the tops. This would certainly
> account for the much heavier concentration of super cooled moisture.
> There was no question the really heavy icing was right at the tops -
> you could hear the stuff applying itstelf.
>
>
> It does take a while for ice to sublimate
> > off...I have picked up ice climbing through a layer out of Seattle that
> > didn't disappear for about 30 minutes, and this was in a Baron.
>
> Sumblimate, yes, but I expected the stuff to fall off pretty quickly
> once the temp was well above freezing. It didn't - probably took a
> long time to warm the plane up.
>
> >
> > Glad that it worked out, though.
> >
>
> Me too.

[john cop]

"Bob Gardner" > wrote in message news:<GwAhb.535167$cF.206989@rwcrnsc53>...
> Look at any text on the atmosphere and you will learn that temperature
> decreases with altitude, cloud cover not withstanding (absent an inversion).
> The sun does not heat clouds.

Look, I am no atmospheric expert, but the above is just a plain silly
statement (less charitable types might say stupid). What do you think
happens to all that energy? It ALL get reflected back into space?

Clouds, which you should know even from just from watching the weather
on TV, are insulators of sorts. This means that the sun's energy (the
part that doesn't get reflected) get absorbed by the cloud as it is
transmitted through it. If were an ideal insulating situation, the
temp gradation would be linear, but, obviously, its not (gas laws and
all that), but the principle is the same. My bet is the energy
transfer to the clouds is greatest at the tops and reduces with
altitude according to some unknowable (too many variables) function.
If your statement were correct, the temp at the tops would be the same
during the day as during the night which is, I think, silly. This
does not mean the temp is going to rise as you climb (gas laws again).
What is does mean is that the cloud's capacity to absorb moisture (or
supper cooled stuff) very near the tops could be substantially greater
than near the bottoms.

[Bob Gardner]

Read this, and google on cloud temperatures.

http://www.cpc.ncep.noaa.gov/products/stratosphere/uv_index/uv_clouds.html

When you look at a satellite shot, the whitest clouds are the coldest....at
their tops.

I have attended a whole bunch of international icing conferences hosted by
the FAA, with meteorologists and aerodynamicists from all over the world in
attendance, and I have read the papers they presented at those conferences.
I have written and lectured on airframe icing. Simply stated, you are wrong.

Bob Gardner

"john cop" > wrote in message
om...
> "Bob Gardner" > wrote in message
news:<GwAhb.535167$cF.206989@rwcrnsc53>...
> > Look at any text on the atmosphere and you will learn that temperature
> > decreases with altitude, cloud cover not withstanding (absent an
inversion).
> > The sun does not heat clouds.
>
> Look, I am no atmospheric expert, but the above is just a plain silly
> statement (less charitable types might say stupid). What do you think
> happens to all that energy? It ALL get reflected back into space?
>
> Clouds, which you should know even from just from watching the weather
> on TV, are insulators of sorts. This means that the sun's energy (the
> part that doesn't get reflected) get absorbed by the cloud as it is
> transmitted through it. If were an ideal insulating situation, the
> temp gradation would be linear, but, obviously, its not (gas laws and
> all that), but the principle is the same. My bet is the energy
> transfer to the clouds is greatest at the tops and reduces with
> altitude according to some unknowable (too many variables) function.
> If your statement were correct, the temp at the tops would be the same
> during the day as during the night which is, I think, silly. This
> does not mean the temp is going to rise as you climb (gas laws again).
> What is does mean is that the cloud's capacity to absorb moisture (or
> supper cooled stuff) very near the tops could be substantially greater
> than near the bottoms.

[Craig Prouse]

john cop wrote:

> Look, I am no atmospheric expert, but the above is just a plain silly
> statement (less charitable types might say stupid). What do you think
> happens to all that energy? It ALL get reflected back into space?

If you think about the characteristics of glass in the visible spectrum, and
consider that clouds behave similarly in the infrared, you might be a little
more charitable.

[Roger Halstead]

On 10 Oct 2003 16:45:47 -0700, (john cop) wrote:

>"Bob Gardner" > wrote in message news:<GwAhb.535167$cF.206989@rwcrnsc53>...
>> Look at any text on the atmosphere and you will learn that temperature
>> decreases with altitude, cloud cover not withstanding (absent an inversion).
>> The sun does not heat clouds.
>
>Look, I am no atmospheric expert, but the above is just a plain silly
>statement (less charitable types might say stupid). What do you think
>happens to all that energy? It ALL get reflected back into space?
>

Not all, but in general, clouds reflect much more light and energy
back into space. They insulate the lower levels, but prevent the
sun's heat from reaching the earth.

Cloudy nights tend to be warmer, but cloudy days tend to be cooler.
Transversely, clear nights are colder and clear days tend to be
warmer.

<snip>

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)

[Bob Gardner]

Here's another picture to look at:

http://www.nws.noaa.gov/sat_tab.html

Bob Gardner

"john cop" > wrote in message
om...
> "Bob Gardner" > wrote in message
news:<GwAhb.535167$cF.206989@rwcrnsc53>...
> > Look at any text on the atmosphere and you will learn that temperature
> > decreases with altitude, cloud cover not withstanding (absent an
inversion).
> > The sun does not heat clouds.
>
> Look, I am no atmospheric expert, but the above is just a plain silly
> statement (less charitable types might say stupid). What do you think
> happens to all that energy? It ALL get reflected back into space?
>
> Clouds, which you should know even from just from watching the weather
> on TV, are insulators of sorts. This means that the sun's energy (the
> part that doesn't get reflected) get absorbed by the cloud as it is
> transmitted through it. If were an ideal insulating situation, the
> temp gradation would be linear, but, obviously, its not (gas laws and
> all that), but the principle is the same. My bet is the energy
> transfer to the clouds is greatest at the tops and reduces with
> altitude according to some unknowable (too many variables) function.
> If your statement were correct, the temp at the tops would be the same
> during the day as during the night which is, I think, silly. This
> does not mean the temp is going to rise as you climb (gas laws again).
> What is does mean is that the cloud's capacity to absorb moisture (or
> supper cooled stuff) very near the tops could be substantially greater
> than near the bottoms.

[john cop]

"Bob Gardner" > wrote in message >...
> Read this, and google on cloud temperatures.
>
> http://www.cpc.ncep.noaa.gov/products/stratosphere/uv_index/uv_clouds.html
>
> When you look at a satellite shot, the whitest clouds are the coldest....at
> their tops.

That is not inconsistant with anything I said.
>
> I have attended a whole bunch of international icing conferences hosted by
> the FAA, with meteorologists and aerodynamicists from all over the world in
> attendance, and I have read the papers they presented at those conferences.
> I have written and lectured on airframe icing. Simply stated, you are wrong.
>
> Bob Gardner

Whow, does this mean you get to ignor the laws of physics or do you
get to rewite them?

-The sun does not heat clouds.-

For this to be true, the clouds would have to be perfect transmitter
of all the radiant energy that wasn't reflected. You know thats not
true from the simple fact that it gets darker as you decend into the
cloud. Its a silly statement.

[JimC]

This is an interesting discussion. I wonder if there might be some mixing
of terms that is adding to the confusion. Let's see if we can agree on a
few basics and take it from there.

The dominant part of the sun's emissions that supplies heating to the earth
is in the infrared end of the spectrum. While there are materials that
approach being 100% IR transmissive, water is not one of them. IR is
quickly absorbed in water. This is evidenced by the spectrum of light
present as water thickness is increased. For example, the deeper part of a
swimming pool appears bluer than the shallow part because the sun's light
has transition through more water, 2 x the depth, before reaching our eyes.
The deeper the water, the bluer and darker it looks (provided the water is
clear).

Does a cloud absorb IR radiation? Well, it's made up of water and water
absorbs IR. The answer is yes, clouds absorb IR radiation. If you have any
doubt, think of being outside on a hot day and what happens to the heat you
feel from the sun when a cloud passes overhead. The heat on your skin from
the sun drops significantly if the there is any thickness to the cloud.

This does not refute the thermal satellite imagery in any way. The
satellite imagery shows IR emissions. The earth's surface is much warmer
than the cloud tops and the earth has pretty high IR emissivity. It
registers as warmer due to its higher IR emissions.

Temperature vs altitude within clouds is a different matter and is affected
by several factors, some of which, like convective cooling, may overwhelm
the others.

Just another 2 cents into the discussion.

JimC

"Bob Gardner" > wrote in message
news:54Ihb.536556$cF.207547@rwcrnsc53...
> Here's another picture to look at:
>
> http://www.nws.noaa.gov/sat_tab.html
>
> Bob Gardner
>
> "john cop" > wrote in message
> om...
> > "Bob Gardner" > wrote in message
> news:<GwAhb.535167$cF.206989@rwcrnsc53>...
> > > Look at any text on the atmosphere and you will learn that temperature
> > > decreases with altitude, cloud cover not withstanding (absent an
> inversion).
> > > The sun does not heat clouds.
> >
> > Look, I am no atmospheric expert, but the above is just a plain silly
> > statement (less charitable types might say stupid). What do you think
> > happens to all that energy? It ALL get reflected back into space?
> >
> > Clouds, which you should know even from just from watching the weather
> > on TV, are insulators of sorts. This means that the sun's energy (the
> > part that doesn't get reflected) get absorbed by the cloud as it is
> > transmitted through it. If were an ideal insulating situation, the
> > temp gradation would be linear, but, obviously, its not (gas laws and
> > all that), but the principle is the same. My bet is the energy
> > transfer to the clouds is greatest at the tops and reduces with
> > altitude according to some unknowable (too many variables) function.
> > If your statement were correct, the temp at the tops would be the same
> > during the day as during the night which is, I think, silly. This
> > does not mean the temp is going to rise as you climb (gas laws again).
> > What is does mean is that the cloud's capacity to absorb moisture (or
> > supper cooled stuff) very near the tops could be substantially greater
> > than near the bottoms.
>
>

[john cop]

Thank you. Makes sense.

In my little experience, the icing was ferocious within, in seemed,
the top 10 ft of the cloud (it was probably more like 100 to 500 but
who knows – it was 20 years ago and I wasn't taking notes at the
time). I always assumed that it was the sun heating the vapor,
droplets, whatever, and forcing them to a higher altitude so they were
a very nearly at their super cooled limit. The dividing line between
ferocious and minimal icing conditions was sharp and very pronounced
during the decent which suggested to me, that sun heating (energy
transfer, if you prefer) was the cause or at least a significant
contributing factor.

[JimC]

In your description of the weather it sounds as though the tops were
increasing in altitude. That suggests lifting agents, e.g. a front or
convective activity, were present. With air movement of that variety it
isn't likely that IR radiation absorption would be able to generate a
stratified effect like you describe. It's more likely that the moisture
near the top was the coldest from convective cooling and was therefore able
to generate the most ice. As you descended you probably encountered
increasing temps, resulting in reduced icing.

Just an educated guess.

JimC

"john cop" > wrote in message
om...
> Thank you. Makes sense.
>
> In my little experience, the icing was ferocious within, in seemed,
> the top 10 ft of the cloud (it was probably more like 100 to 500 but
> who knows - it was 20 years ago and I wasn't taking notes at the
> time). I always assumed that it was the sun heating the vapor,
> droplets, whatever, and forcing them to a higher altitude so they were
> a very nearly at their super cooled limit. The dividing line between
> ferocious and minimal icing conditions was sharp and very pronounced
> during the decent which suggested to me, that sun heating (energy
> transfer, if you prefer) was the cause or at least a significant
> contributing factor.

[Bob Gardner]

I don't have "little experience" flying in icing conditions...I have a lot
of experience flying pistons, turboprops, and jets in an area of the country
so prone to icing (on the west slopes of the Cascades) that the Concorde was
sent out here for icing certification...I flew media folks to Grant County
airport for the occasion.

A good source of information would be Dr. Marcia Politovich at the National
Center for Atmospheric Research in Boulder, Colorado ).
She is known in the aviation meteorology community as the Ice Queen, and has
lots of experience flying in icing research airplanes....but then again you
are not impressed by credentials.

Bob Gardner

"john cop" > wrote in message
om...
> Thank you. Makes sense.
>
> In my little experience, the icing was ferocious within, in seemed,
> the top 10 ft of the cloud (it was probably more like 100 to 500 but
> who knows - it was 20 years ago and I wasn't taking notes at the
> time). I always assumed that it was the sun heating the vapor,
> droplets, whatever, and forcing them to a higher altitude so they were
> a very nearly at their super cooled limit. The dividing line between
> ferocious and minimal icing conditions was sharp and very pronounced
> during the decent which suggested to me, that sun heating (energy
> transfer, if you prefer) was the cause or at least a significant
> contributing factor.

[LB]

I'm currently inactive also....
Same thing happened to me about the same time same place almost same
airplane! I had a M20-E (super). I don't think we had all the training and
information that's available today. Much had to be learned by doing.
I recall one night leaving Boston on a snowy night around 11 PM. I got a
weather brief from the FSS and filed.. They told me there was an inversion
with altitude. After taking off I felt uncomfortable with the snow because
of the St. Elmo's effect. I saw the glowing arc from the propeller and the
arcing on the windshield so I requested and got another higher
altitude(7000) from Boston center. This put me into solid cloud cover with
34 deg OAT. After 5 minuets or so I noticed my airspeed slowing. I looked at
the wings with my flashlight and saw ice building. I then requested a higher
altitude (9000). This didn't change the temperature. It only made matters
worse. I heard a howling noise and a bang. My ADF antenna broke off. I
looked again at the wing and saw ice "horns" about 3 inches long building on
my nav lights. I then requested a higher altitude (11000) and applied full
power to start a climb. I couldn't get any higher than 9500 ft or so. Not
knowing what else to do I pushed the prop control into a flat pitch to try
to bend the blades and break any ice off. This must have worked because I
heard some banging and my airspeed came up a little. I told Boston of my
problems and they cleared me to 13000. At that time an Eastern Capt. came
back to me and told me he was at 16000 picking up heavy ice. I told Boston I
can't fly anymore with full power I was descending 200 fpm. and need a
vector to the closest airport. They steered my to Hartford and I made one of
the quickest approaches in my life. I had to land crabbing looking out the
small open storm window on the pilot side because the windshield iced over..
I kept the IAS over 110 in case the ice would spoil the lift. Upon landing
the attendant directing me with his flashlight remarked "Whooeee where the
hell was I? I saw this in books but not in real life!" I had over 3 inches
of ice on the leading edges and the breather was fully blocked. The small
alternate air door automatically opened. I looked up at the sky and it was
perfectly clear. I went through the weather and didn't even notice. I think
in retrospect I should have stayed in the snow. I'm very grateful that I had
a Mooney. Not that It's better, it's just because it got me through it. The
rat at Hartford deiced my plane in their heated hanger and charged me $50
bucks! Since then I never fully believed the FSS I made damn sure I got at
least one pirep and I personally looked at the weather maps before leaving.
"john cop" > wrote in message
om...
> Have been inactive for many years.
>
> About 20 years ago, when flying up from the south, I got suckered in.
> The tops slowly rose untill I was flying at over 15,000 (Mooney 201)
> near Cleveland, It was clear on top and the temp was in the mid 40s
> on the ground, and the freezing level was high enough so I wasn't
> worried.
>
> When cleared for decent, ice formed at an incredible rate - must have
> picked up over an inch of rime in seconds near the tops. Once below
> the sun heated top layer, the accumulation virtually quit. Breaking
> out below at about 4,000, the temp was already well above freezing,
> but no ice was dissapearing.
>
> While being vectored into the approach, I ran some test to make sure
> the plane was behaving normally and was capable of climbing. On hind
> site, I should have refused the approach clearance and waited for the
> ice to fall off.
>
> Anyhow, after having read accounts about people stalling on final and
> etc., I brought her in about 20 knots fast over the numbers and
> chopped everything. I damn near overran a 5,000 ft. runway - the
> sucker didn't want to land.
>
> Rime ice, I have since found, can lower the stall speed (raises the
> dragg). It increases the leading edge of the wing. This was verified
> by test I did for a senior project in a wind tunnel using an airfoil,
> rubber cement, and sugar. The Reynolds number was way off for that
> test, so it could be suspect. However, I had occassion to take to one
> of the crew of the icing planes over at NASA who confirmed all this
> and it sure would account for my landing problem above.
>
> Anyhow, after parking the plane, ice was still falling off in big
> chunks for 10 or 15 min.




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[Icebound]

john cop wrote:
> Thank you. Makes sense.
>
> In my little experience, the icing was ferocious within, in seemed,
> the top 10 ft of the cloud (it was probably more like 100 to 500 but
> who knows – it was 20 years ago and I wasn't taking notes at the
> time). I always assumed that it was the sun heating the vapor,
> droplets, whatever, and forcing them to a higher altitude so they were
> a very nearly at their super cooled limit. The dividing line between
> ferocious and minimal icing conditions was sharp and very pronounced
> during the decent which suggested to me, that sun heating (energy
> transfer, if you prefer) was the cause or at least a significant
> contributing factor.

The reason that the top portion of a cloud may produce the most icing...
is that the cloud's formation process has resulted in the most liquid
water near the top.

The formation of most clouds is the result of lift, and as air lifts it
cools at a very substantial rate. When the dewpoint is reached, the
condensation occurs. As the air lifts more, the air becomes colder and
has less capability to support water vapour... hence more
condensation. If the air near the top of the cloud was lifted the
furthest, then that is the air where the most liquid has been condensed.

The fact that the sun may heat the top of the cloud a little, actually
works against icing. By raising the temperature slightly, the air can
support more vapour, and some of the liquid will evaporate.



--
God grant me the serenity to accept the things I cannot change, the
courage to change the things I can, and the wisdom to know the difference.
--- Serenity Prayer

[Tarver Engineering]

"Icebound" > wrote in message
ble.rogers.com...

<snip>
> The fact that the sun may heat the top of the cloud a little, actually
> works against icing. By raising the temperature slightly, the air can
> support more vapour, and some of the liquid will evaporate.

Liquid evaporating making cold. :)

A cloud can absorb energy without gaining temperature.