Haze layer, smooth on top - what's it called?

RyanB

RyanB

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Forgive my ignorance, I've noticed this faintly thin haze layer if you will, and I'm not talking about this wildfire smoke, it's there with or without smoke in the air. I've noticed once above it, it's always nice and smooth and once you descend below it, it starts to get bumpy again. What's the science behind it?
 
Salty said:
temperature inversion?
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I don't know. According to the Winds Aloft/Temp forecast, there isn't an inversion, but I dunno. Seems I've noticed it more during the summer and it’s very predictable. I see a thin haze layer as I’m climbing and always know once I get above it, it’s gonna be smooth air.
 
When I was flying in the east coast I just called it the haze layer
 
Initial Fix said:
When I was flying in the east coast I just called it the haze layer
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That’s what I’ve always called it too, just curious if there’s more of a proper term for it and what it actually is.
 
This is from the Jeppesen Private Pilot textbook:
"In some cases, you can find relief (from convective turbulence) by climbing into the capping stable layer which begins at the top of the convective layer. This can sometimes be identified by a layer of cumulus clouds, haze, or dust."
 
More heat dome than inversion, I’d say. Pretty standard summer weather pattern in the SE region, just early this year. Usually we spend the summer on the western edge of the oppressive Bermuda High.

In this case, a very strong & stubborn high at ~10,000 ft is supporting two lower level highs in the SE. These surface highs have very weak circulation. So smoke, ozone, & pollutants are trapped near the surface with no where to go, hence the haze.

This near permanent weather feature of summer in the SE, coupled with the hill & dale nature of the ground, is the reason the SE has the highest childhood asthma rate in the nation.

but the ride is nice above it. (I did some screenshots of the winds at 10k & the surface, but can’t get them to upload).
 
RyanB said:
Forgive my ignorance, I've noticed this faintly thin haze layer if you will, and I'm not talking about this wildfire smoke, it's there with or without smoke in the air. I've noticed once above it, it's always nice and smooth and once you descend below it, it starts to get bumpy again. What's the science behind it?
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Summer haze usually occurs when there is a temperature inversion aloft that traps micron-size pollutant particles in the lower atmosphere. These particulates are hygroscopic (attract water) and can grow large enough to significantly scatter light, even below the dew point. It's bumpy below because that portion of the atmosphere is still subject to ground-heating convection which helps stir up pollutant particles. It is smooth above because you are above the inversion boundary, and convection is capped at the inversion. The inversion boundary also helps trap the pollutant particles in the lower atmosphere. If you can get above the haze layer, the ride is always nicer and the view is crystal clear, but some days this haze layer tops out at altitudes not easy to attain in a light single.
 
chemgeek said:
Summer haze usually occurs when there is a temperature inversion aloft that traps micron-size pollutant particles in the lower atmosphere. These particulates are hygroscopic (attract water) and can grow large enough to significantly scatter light, even below the dew point. It's bumpy below because that portion of the atmosphere is still subject to ground-heating convection which helps stir up pollutant particles. It is smooth above because you are above the inversion boundary, and convection is capped at the inversion. The inversion boundary also helps trap the pollutant particles in the lower atmosphere. If you can get above the haze layer, the ride is always nicer and the view is crystal clear, but some days this haze layer tops out at altitudes not easy to attain in a light single.
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Are you saying the inversion is above the layer or below the layer?
 
RyanB said:
That’s what I’ve always called it too, just curious if there’s more of a proper term for it and what it actually is.
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I don’t think ‘it’ has like an official name. But a temperature inversion can cause it. If there is a name for it you could find it in one of those METAR/TAF decode lists. I ain’t lookin, maybe someone will.
 
In my 29 years of flying we've always just called it the top of the haze layer. It usually corresponds with the tops of a cumulus layer when scattered clouds start to develop.
My best attempt to identify the altitude of that point is by looking at the Skew-T log P temp & dewpoint graph, when the red and blue lines start to spread apart. I'm sure there's a more scientific way to determine it, but I'll leave that to the met geeks.
 
chemgeek said:
Summer haze usually occurs when there is a temperature inversion aloft that traps micron-size pollutant particles in the lower atmosphere. These particulates are hygroscopic (attract water) and can grow large enough to significantly scatter light, even below the dew point. It's bumpy below because that portion of the atmosphere is still subject to ground-heating convection which helps stir up pollutant particles. It is smooth above because you are above the inversion boundary, and convection is capped at the inversion. The inversion boundary also helps trap the pollutant particles in the lower atmosphere. If you can get above the haze layer, the ride is always nicer and the view is crystal clear, but some days this haze layer tops out at altitudes not easy to attain in a light single.
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Oh yeah. I’ve seen the evolution of Los Angeles basin smog. From yellow sky to it getting better over the course of years after the California smog rules for autos in the 70’s, maybe 60’s. It was a dramatic change. In recent years it seems to be kinda coming back. Cars are cleaner now, but there a whole lot more of them.
 
Brad Z said:
My best attempt to identify the altitude of that point is by looking at the Skew-T log P temp & dewpoint graph, when the red and blue lines start to spread apart. I'm sure there's a more scientific way to determine it, but I'll leave that to the met geeks
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My best guess is "temperature inversion" also. the forecast are just that and based at specific location. I am currently at a sailplane racing competition, (Region 8 Soaring Championship). Before the soaring forecast got at good as they are we used to take the towplane up in the morning with a thermometer and measure the temperature every 500 feet so we could get our own sounding for the local airport. We still have a wet bulb thermometer we used to use also on display in our facility, I don't think we took it up in the towplane, but just did a ground reading with it.

I have frequently noted temperature inversions when the vents or window/door(J-3) is open and I can fell the difference. If you have a good digital or accurate thermometer you might be able to observe the inversion on it as well.

Brian
CFIIG/ASEL
N1720 "GG" LS6b
 
dmspilot said:
Are you saying the inversion is above the layer or below the layer?
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Warmer air over colder air, that is what a temperature inversion is in the oversimplified version. (Normally air gets colder with altitude due to adiabatic expansion.) Temperature inversions inhibit convection. The haze layer boundary is typically at the altitude where the cooler air below reaches the dew point.
 
"Haze layer, smooth on top - What's it called?"

A Summer morning in the South?
 
chemgeek said:
Warmer air over colder air, that is what a temperature inversion is in the oversimplified version. (Normally air gets colder with altitude due to adiabatic expansion.) Temperature inversions inhibit convection. The haze layer boundary is typically at the altitude where the cooler air below reaches the dew point.
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I didn't ask you what a temperature inversion was. I asked you WHERE it was. Are you saying the inversion starts at the top of the haze layer, or below it?
 
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chemgeek said:
Warmer air over colder air, that is what a temperature inversion is in the oversimplified version. (Normally air gets colder with altitude due to adiabatic expansion.) Temperature inversions inhibit convection. The haze layer boundary is typically at the altitude where the cooler air below reaches the dew point.
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That is called the base of the clouds. :) Which many times is the top of the haze layer, but it may not be.

You don't need an inversion to cause the haze layer to stop. It can be a change in the lapse rate such that there is no longer vertical movement to expansion of the air as the pressure reduces.
 
Pinecone said:
It can be a change in the lapse rate such that there is no longer vertical movement to expansion of the air as the pressure reduces.
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That sounds like it would occur at the level of the temperature inversion.
 
Salty said:
That sounds like it would occur at the level of the temperature inversion.
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Yes, a significant positive deviation from the adiabatic lapse rate, which in oversimplified form is warmer air over colder, which confers vertical stability preventing further convection.
 
From July AOPA Flight Training magazine, "Once that air hears up, turbulence is near constant unless you can climb above the haze layer. "
 
dmspilot said:
I didn't ask you what a temperature inversion was. I asked you WHERE it was. Are you saying the inversion starts at the top of the haze layer, or below it?
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The inversion is below the top of the haze layer. The inversion is from the ground up where the temperature rises versus decreasing at the adiabatic lapse rate. The inversion ends where the temp curve begins to decrease versus rising.
 
Rcmutz said:
The inversion is below the top of the haze layer. The inversion is from the ground up where the temperature rises versus decreasing at the adiabatic lapse rate. The inversion ends where the temp curve begins to decrease versus rising.
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There can't be convective turbulence and cumulus clouds inside a temperature inversion. So that is not correct.
 
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RyanB said:
I don't know. According to the Winds Aloft/Temp forecast, there isn't an inversion, but I dunno. Seems I've noticed it more during the summer and it’s very predictable. I see a thin haze layer as I’m climbing and always know once I get above it, it’s gonna be smooth air.
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The inversion is too shallow to show up on a Winds Aloft forecast. This chart from last week shows an inversion around 700mb (~9,000 feet), looks like it's not even 1,000 feet thick before the lapse rate returns to normal.

RNK-skewt.gif
 
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Salty said:
That sounds like it would occur at the level of the temperature inversion.
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Inversion means the air gets warmer as you go higher. Change in lapse rate means the air gets colder or hotter than normal as the altitude changes. Different things.
 
dmspilot said:
There can't be convective turbulence and cumulus clouds inside a temperature inversion. So that is not correct.
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That would be news to me when I'm in a thermal below the inversion. Looking at the haze domes near the top to find the next one. Very common in FL in the morning, thermal tops rise as the inversion dissipates.
 
Someone please make an app which gives me the answer for $10 a year k thx
 
scottd said:
It is called a subsidence inversion. Sinking air causes the top of the subsiding layer to compress more, and therefore, more adiabatic compression means the top gets warmer than the bottom creating the inversion.
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You are the MAN! Thank you!
 
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