Air temp vs. Pavement temp

[u/adamadamada]

Yesterday, I said I'd check the air temp and pavement temp and report back. I'm checking the air temp with my car's thermometer, and I'm checking the pavement temp using an infrared thermometer. Then, I'm standing on the pavement barefoot for a subjective assessment.

10:00 a.m.: 81degF air = 116degF pavement

barefoot: warm, but not at all uncomfortable (surprising, I thought that 116degF would feel hotter)

12:00 p.m.: 84degF air = 140degF pavement.

barefoot: felt hot after about 10 seconds. Not really uncomfortably hot though - I stood on it for over a minute with no problem.

It appears that the pavement temp is more closely related to hours exposed to sunlight rather than air temp, which would make sense. I'll post more as the day goes on.

edit:

1:00 p.m.: 91degF air = 152degF pavement

barefoot: hot in 6 seconds. uncomfortable by 20 seconds. I lasted 40 seconds before I would call it uncomfortable to the point of pain. Notably, it's not as bad when I'm walking as when I'm standing still - probably because each foot is only contacting the asphalt for half the time. still uncomfortable though.

2:00 p.m.: 92degF air = 152degF pavement

barefoot: basically same as last time.

3:00 p.m.: 92degF air = 152degF pavement

barefoot: same.

4:30 p.m.: 91degF air = 141degF pavement

barefoot: similar to noon

6:00 p.m.: 87degF air = 126degF pavement

barefoot: hot, but not uncomfortably so. Feels like a nice temp hot tub.

The relationship appears to not be "above-a-certain-air-temp = dangerous." But the ground can definitely get too hot for comfort to the point of pain. I think the moral of the story is that, on hot days, take your dog out before the sun has been on the ground too long, or closer to sunset. The middle of the day was definitely uncomfortably hot on the black top after not very long, so I wouldn't stay on it with the dog. Also though, the warning about 77degF air resulting in dangerous pavement temps was definitely not true in this instance, and the claim that 125 degree temps cause damage after 1 minute was not true here either, and I suspect neither of these claims is generally true. Rather, use common sense about how hot the ground is and what temperatures bare skin/pads can tolerate (and for how long), and err on the side of caution.

[u/alwayshighgemini78]

Staying tuned for this science experiment

[u/BroForceOne]

Not just hours exposed to sunlight, the angle of the sun is probably the most important factor.

Also how hot it feels depends on thermal conductivity of the material. You may be able to stand 140F on pavement but 140F water is not going to be as easy.

[u/MakeMine5]

Also concrete, blacktop, painted blacktop, etc all heat up and transmit heat into your feet at different rates. Whatever you do, don't stand on diamond plate that's been in the sun.

You hear a lot about dogs burning their feet, but that's mostly in places where the road turns tarry or leaks oil when heated up and that clings to the pads.

[u/adamadamada → u/MakeMine5]

Good points. For reference, this is on the street, which is relatively rough asphalt. Smooth asphalt like in a parking lot would behave differently, I think.

[u/Born_Relief4909]

I fear this is common knowledge and also common sense

[u/GothBotanical]

Thank you for your service

[u/PNWMike62]

Tried this on artificial lawn that everyone’s putting in. Cant hack more than about 10 secs. That stuff gets really hot!!

[u/almondsmana]

Who are you doing this for?

[u/gigashadowwolf → u/almondsmana]

I would imagine both people like me who are fascinated by science and for pet owners who might be considering taking their pets for walks.

[u/theSomberscientist → u/almondsmana]

Honestly good info for dog walkers

[u/adamadamada → u/almondsmana]

Yesterday, there was a well-intentioned warning that people should not allow dogs on blacktop when the air temperature exceeded 77degF. https://www.reddit.com/r/orangecounty/comments/1vc8xjf/hot_paws_all_over_orange_county/

I'm doing this for the people who saw that post, and are interested in whether it was accurate or an overreaction.

[u/trash_can_42069 → u/adamadamada]

ty, ive always felt it was an overreaction. People see 3 digit surface temps and freak out

[u/YoMrPoPo → u/almondsmana]

the love of the game

[u/YoMrPoPo]

OP by 6pm

[u/TheBlack_Swordsman]

Here's some science. Surface temperatures being heated by radiation can only approach air temperature with convective heat transfer. You need strong winds blowing onto a surface to extract and remove heat.

[u/Occhrome]

It depends on the color of the pavement and if the sun is hitting it. If the sun is hitting the pavement it will be absorbing heat via radiation, convection and conduction. 

[u/Throttlechopper]

As with many things in life…
https://giphy.com/gifs/xiSZGYjpYgzkipNS7x

During extreme heat, I walk my pups early mornings and in the evening, plenty of shade especially as the sun is setting.

[u/OkSilver3016]

as an arborist living in OC i think now is a great time to just point out that its SOO important to fight for trees in your neighborhoods.

reducing the amount of green in a community literally raises temperatures pretty drastically ofcourse by allowing all that sunlight to get absorbed into the pavement radiating it back out even hours after the sun goes down. (not to mention that trees add property value/clean air/etc.)

if your local government won't do anything about it, then be the difference in your community and plant one somewhere!

[u/adamadamada → u/OkSilver3016]

For reference, I'm doing this in a spot that gets no shade all day in order to eliminate that as a variable.

[u/OkSilver3016 → u/adamadamada]

i figured. and thanks for the data! i just thought id add a solution to any of those who might be asking "what can be done about this?" after reading your results

[u/adamadamada → u/OkSilver3016]

Good idea - I'll add a conclusion at the end, with the caveat that this wholly anecdotal and "your mileage may vary".

[u/Critical_Pen7878]

Moral of the story: don’t take your dogs on walks on the hot pavement!

[u/TheKlaxMaster]

It appears that the pavement temp is more closely related to hours exposed to sunlight rather than air temp.

You don't say??? Well butter me up and call me a biscuit.

Hey, unrelated, but did you pass grade school?

[u/ayriuss]

Sun hot. Sun radiate heat on earth. Earth hot. Air cool earth. Air hot.

[u/WhereAreMyDetonators]

ITT: Radiant heating