I’m back from my road trip today. It was a day of surprises, I visited 5 weather stations today, and each had a story to tell.
The one that was the most surprising is represented by the photo below, which I snapped with my Infrared camera. Hint: it’s not asphalt. The reading of 66°C for some elements in the scene is accurate. And it’s at an operating USHCN station, right under it in fact.
I’ll have more on this tomorrow, and a corresponding visible light photo that tells the story, right now I’m dead tired from driving 300+ miles today.
UPDATE: Lot’s of guesses, no correct answers. Click below to see what it is. You’ll be surprised. I sure was.
Fresh wood chips over weedmat at an official NOAA/NWS station, which is also a USHCN station. Surprisingly, note that the concrete is actually cooler in the IR photo. The work was ongoing, which is why the gate was open and the sign is not affixed yet.
More on this station soon in a new post.
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(“Hanson’s forehead . . . . “!)
You only had to drive 300+ miles to obtain measurements from the Phoenix Mars Lander? Must be a hoax.
[snip no ad homs here]
Penelope Cruz?
Looks like the woodchips are on black plastic. The blast plastic catpures the heat and the wood chips insulate the black plastic.
In Texas, they were using woodchips as padding for the little feet on kids playgrounds to save money vs gravel or shredded tires.
The problem they had was that the woodchips would get so hot that they would spontaneously combust. Part of this was due to biological activity when the chips would get wet – and part was due to the insulating nature of the chips themselves.
Did you take it in a National Park or something similar?
I’m not surprised the ground reads hotter that the concrete. Mulch holds in a lot of moisture, that’s one of it benefits and in the case of temperature reading, one of it’s downfalls.
The painted I-beam would be the hottest object in the pic from sun-warming; it reads a “cool”… 120 degrees Fahrenheit??! Got me!
The green grass bothers me. I lived in Addo, Eastern Province, South Africa, for several years where the temperatures reached 40C regularly, but no ways could we keep the grass green during the summer heat. We watered the grass regularly.
Was this an exceptionally hot day?
Black only “attracts” heat if it is directly exposed to the light sourse. Black’s skill is only absorbing light as apposed to reflecting it. I think this may be a result of decay. Freash wood chips are usualy in active fermentation, hence the horrible smell associated with them. This proces produces thermal energy. Not sure if this accounts for the whole temperature difference, but it is deffinatly part of the equasion. Would be interesting to see the thermal image from there a few months from now.
Who’d a thunk — mulch as a siting issue. But it makes sense as mulch ‘cooks’ much the same as compost. Bet its greatest impact would be at night. I suspect that whoever came up with the idea of the mulch had no thought of the effect its use would have in generating heat and any impact on instrumentation; it just looks nice and is low maintenance.
With that “weed mat” under it is probably no different than tanbark chips spread on asphalt. It’s still going to get hot. It looks like a pretty thin layer of chips, too.
Jeff (08:11:30) :
At 150F, I doubt there are many microbes lunching there. IIRC, composting tops out around 120F, I assume spontaneous combustion comes from subsquent chemical reaction. Anyone with a clue with numbers an chemistry is welcome to correct me. How deep were the wood chips?
It may be that the long wavelengths of infrared light (possibly including IR reradiated from the wood chips) are making it through the chips to the plastic. The IR the camera is responding to may be coming from just below the chip surface. I would expect the visible surface to be closer to ambient temps.
Pure speculation. I have an electronic meat thermometer, small size wood chips, and maybe some black plastic at home. I’m tempted to measure the temperature profile of various thicknesses of chips.
Makes the camera worth the price tag. Good purchase!
The weedmat vendor might have that information already.
Umm, why wasn’t the station installed on terrain typical for the area?
Now on days that the sprinklers run, or after dew… That stuff will absorb water, and be cooler than otherwise for hours.
“The work was ongoing…” Ah, you caught them in the act of “adjusting” temperatures (a/k/a man-made global warming). There’s no such thing as privacy anymore, even for gov’t agencies. 😉
Anthony,
Have you double checked IR-measured temperature of wood chips using thermometer? It might just be possible that there is a large emissivity difference between concrete and mulch which would fool IR camera.
I wonder
REPLY: I didn’t have a hand held thermometer with me but two things confirmed the IR photo:
1) I touched both the concrete and the nearby woodchips, woodchips definitely were hotter to the touch.
2) Walking around taking photos, I could feel thermals rising off the wood chips, but none when I was over grass.
Richard111,
I get green grass on my asphalt driveway in the middle of summer! And not always in the yard…
Woodchips are dark and are simply absorbing the IR. Not much different than dark asphalt, except to a lesser degree. I have walked bearfoot on wood chips in the sun and they do get quite hot.
The black weed cloth, if not exposed, has no effect on the direct incoming IR, but may have some insulating effect that slows any downward (cooling) heat conduction into the earth. Also, radiation occurs internal to the chips, and the weed cloth (being darker than chips) should absorb more downward radiation versus upward chip radiation within the pile.
Regarding moisture effects, if the chips are wet, evaporation should cool them, however, the moisture should also increase the heat (storage) capacity of wet chips vs dry chips. Another moisture effect is near surface and “in pile” air gap greenhouse warming from the water vapor.
I might then surmise that the extra heat capacity, near surface and intra pile water vapor greenhouse warming, and downward conduction insulation is outweighing the evaporative heat loss.
Some info about compost piles, from RRS, a commercial composting outfit:
“Compost piles that don’t reach the temperatures that indicate active composting will take much longer to fully decompose. The ideal temperature range for active composting is 105-145º F. Compost piles that have not heated up within three days of being formed should be considered as problematic and in need of adjustment.
“Temperatures greater than 170º F create potential for spontaneous combustion. Mesophilic (likes to grow under medium conditions of moisture) organisms thrive from 104°-122°F and their activity is inhibited outside of this range. moisture) organisms thrive from 104°-122°F and
their activity is inhibited outside of this range. High temperatures can be the result of compost piles that are too big or too dry, and from lack of heat removal due to insulation or aeration.”
http://www.recycle.com/pdfs/temperature.pdf
Wet wood chips would likely do the same thing.
Interesting observation: look at the comparable temperature of grass (a few blades of it against the forward edge of the concrete base). They remain pretty cool compared to the rest of the environment.
REPLY: Yes, I have other photos showing this contrast – they’ll be in a subsequent post. – Anthony
Call Yilmaz!
The matting underneath is the most striking part of the image. The white flares in the picture seem to be associated with it. It seems illogical that the matting under the chips would be hotter than the chips. It might have a higher emissivity than the chips but I doubt that it would be a lot higher. I assume the chips have a very high emissivity due to the incredible surface area they have.
I don’t see any black spots caused by shiny objects reflecting the sky. Was it overcast?
Thermography can be very tricky.
REPLY: Full sun when that photo was taken. – Anthony
We know wood chip piles can spontaneously combust (not many things do) and this seems to be somewhat random in that not all large wood chip piles combust while smaller ones sometimes do.
I guess the IR photo shows why that is the case.
Might be some new science here that has rather large implications for gardeners, farmers, landscapers, the forest industry, biologists and, of course, climatologists and weather station monitors.
I propose that the NCDC and GISS make a new (negative) adjustment to the temperature record for the increase in wood chips used around temperature sensors.
I’m quite surprised at how much the shadow from the fence cooled things off.
My guess is that the fresh wood chips – and “fresh” is the key – are spontaneously heating. The rate of heating will decline over time as the chips oxidise.
How many chips would a woodchip chip if, oh never mind . . .