air temp vs. surface temp

i've been a snake owner for over 20 years and for the first time today i had a thought. what is the relationship of air temp to surface temp? do you check ambient air? surface? both? i take my temp with a digital thermometer about 1" above the subsrate in the hot spot which is over the UTH and under a lamp. its generally right at 90. the probe fell off the side of the tank and was laying on he ground earlier and it read over 100 and thats what made me think about this. since surface temps are always higher than air temps, what is the proper surface temp?

I had the same issue recently. I finally bought a IR temp gun and found my surfaces hotter than I thought they were as well. I now maintain my hotspot with my IR temp gun and make sure my ambient temps are around 80 using both digital and analog wall hanging thermometers.

As long as you have a hot spot of 90 degrees (surface temp) the air temperature in the entire cage can be 80 degrees.

Where is your UTH's thermostat probe? UTH's do not change the temperature of the air in the cage only the surface temps.

Snakes have a long lung (the other if it has one is not as important here) the lung runs past the heart and liver as well as most of the circulatory system runs along it too. If the air temp in the lung from the enclosure is hot or cold the act of thermoregulating becomes problematic. The air in the lung can chill or heat the blood and then the core. The surface temp heats the skin and muscles doing the same thing but to a lesser degree.

I have a pet idea that many burns come from snakes trying to heat the core temp on hot surfaces when the air temp is cool. My vet thinks this is sound but there has never been research on it (good thing burning snakes intentionally does not sit well)

The air temp and surface temps should be monitored but typically I believe that the surface temps should ideally be 80/90ºF (with in a degree or two) and the AIR temp between (ideally) 78-85ºF. Yes they can adjust to lower or higher but ideal temps based on current understanding sit around these values. Younger snakes the temps can be a bit lower and old or sick royals can be a bit higher.

so i suppose that surface temp is the most important to keep in the 90ish range then? if i've been using a lamp to heat the hot spot to 90 at about an inch to inch and a half ABOVE the surfac, its possible that the surface has been too hot, right? that would explain why my snake does not like to hang out there....

Yep. Sounds to me like you have been keeping your hot side way too hot. Its common practice to have a probed digital thermometer right at the hottest point under the substrate so you can monitor the hottest place your snake can reach.

Then you need another thermometer to measure the ambient temps. Most people put this on the cool side.

Whenever you use a under tank heater you absolutely need a thermoSTAT to control it. Otherwise you risk cooking your snake.

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Your snake is a good gauge, I expect snakes to spend most of the time on the cool side and shift if the room drops lower than normal or just after a meal for a few days. If a snake is either 100∞ of the time on the heat or cool and doesn't move after a mea especially I would expect the temp to be incorrect. I find that some prefer it warmer than others they are individuals and so i have differing temps for each animal somewhat. But all are inside the 78-93 range. Ambient air temps in my set ups vary by about 4-6ºF during the night and day. Peaking at around 3pm and lowest at around 2 am.

Measuring both temps is important. Once you have a cage set up, they typically remain relative, unless you make a new change.

As you are finding, surface temps can be much different than air temps when the surface (substrate, basking spot) is directly affected by a heating or cooling element. If you are heating a hot spot or basking area with a light, heat tape or UTH, the surface temperature will reach a set temp. Just a quarter inch ABOVE that surface, the AIR temp may be 10 or 20 degrees LESS than the surface temp. And that is completely valid.

As the temps get higher, you see this more pronounced. In monitor lizard setups, we aim for 130F+ basking surface temps, yet the air temp just an inch higher may be 20-30F LOWER than that surface.

In a snake setup, if you are measuring temps with a digital thermo and probe (which measures air temp) and you find your hotspot to be 92F just a bit over the actual surface, the surface temp itself may indeed be 100+.

When setting the hot spot in a snake setup, a temp gun is definitely the right tool to use.

We use both temp guns and digital thermos in our facility, as they are complimentary tools. It is important to know both surface and air temps.

Tangent to that...

If your surface is NOT affected by direct heating or cooling, then the surface may very well be in equilibrium with the air temp. On the cool end of the cage, for example, substrate surface may indeed measure 75F with a temp gun, while the air temp two inches higher ALSO measures 75F.

It is really useful to measure all three temps. You can buy IR guns with thermocouple that will allow you to measure surface and then switch and measure ambient. The price range on units like this is huge from under 40$ to over 4000. Check the specs IR guns almost always are +/- 2ºF or worse just make sure you are not buying one that is spec'd at 2ºC or 3ºC Thermocouples are often 1ºF or better but sometimes you will see 1ºC which is common for digital thermometers personally I prefer better than 1ºC (2ºF) and tend to pay a touch more for better.

If heat tape doesnt effect ambient air temps then how can it be used in an incubator as the sole heat source? The difference I can think of is a tub is ventilated and an incubator not so much so the heat is trapped/contained.