UKH

La Nina is staying with us at the moment.  She somehow manages to have a peripheral temperature (ears, fingers, toes, nose) colder than room temperature.

How is this possible?  I just about get that nose can use evaporative cooling, but the rest?  Confirmed with a thermometer!

Is she La Diabla?

Oh easily! I'm currently sitting in our centrally heated house wearing a merino t-shirt, merino mid layer, paramo fleece and warm paramo gilet and my fingers are cold! My other extremities aren't too bad at the moment, but can easily get there!

Sure, but how does she...I mean, physics...and metabolism...I mean...what?

Some of us have bodies that really don't believe that keeping us warm is the job of our bodies!! I have a very low resting heart rate and low blood pressure, I have often wondered if those things cause me to be cold. I don't know if they do though, never investigated it!

how are you measuring the temperature of her bits?

What would cause a low body temperature out of interest?

My dad is currently wandering around with 3 thermometers, two at home and one at work and they all read 35.5 degrees and he's constantly cold.

I initially thought that the two at home are dodgy but the one at his work is rather expensive and accurate.

A fridge uses heat to cool it down so perhaps our bodies have a similar process?

Look at diet? If she's a one lettuce leaf type that will have an effect. More protein / carbs in that case; cue a massive diet argument Alternatively depending on age, thyroid activity may be a thing. Finally and most likely, stress. No medical expertise whatever was involved in this post.

My oldest brother had some kind of medical check, beyond the usual one can get through the doctor and the NHS, a part of that was having the temperature his body core and extremities looked at, and he and another person were the only 2 out of many who has especially cold noses, ears and fingers, something to do with their circulation to those parts. El Nina is possibly the same?

Check she has a reflection in a mirror

But how is it possible for the female extremities to achieve a temperature colder than the surrounding environment? Do ovaries have a refrigeration function?

This question has come up with multiple girlfriends over the years and if this period of lock-in provides opportunity for science to explain it then some small good will have come of it. 

I agree.  Yay for science!  Now we need a broad set of volunteers to have their bits measured in rooms of different tempratures....

Water at room temperature will feel cold.

How did you measure the temperature of her fingers etc.?

Cold environment

Body composition. Women have a higher fat to muscle ratio. Muscle generates more heat. Fat insulates us and keeps our core temperature up. 
 

Men will sit around in t-shirts with the heating off while women are wrapped in many layers. 
 

Gives us a real problem in office spaces. 
 

Body temperature is normally between 36.5 and 37.5. That’s core, not surface. And that’s ‘normal’ there will be outliers. It’s useful to take your temperature regularly and build up a graph. It changes throughout the day and, for women, throughout the month. . 

But what I don’t get (seriously) is how they manage to feel colder than the ambient environment. Even without internal heating they shouldn’t be able to be colder than the air, should they? What effect is going on there?

I have never found diet to be a factor. Over the years I have gained weight, lost weight, eaten junk, eaten very healthily, and I am still a cold bunny. I currently eat a MASSIVE smoothie with oats for breakfast (after my morning run or cycle), and protein and veg rich meals for lunch and dinner. I wear 4 layers on my top half as standard and add more if I'm not moving much.

Some of us are just always cold.

Maybe diet does make a difference to some people's body temperature, but it's definitely not a factor for everyone

Our body temperatures are not so much to do with the surrounding temperature (although it clearly has an impact!) but about whether warm blood is being pumped to those blood vessels or not. So if your body decides your core needs to be prioritised then the blood stops flowing to the extremities. 

It's easy for things to feel colder than their ambient environment, the ambient environment often doesn't feel as cold as it actually is because air is a very effective insulator.  That's why 'wind chill' is a thing. 

When you touch something that is cold it'll feel colder if it is a better conductor of heat, because as you lose heat to it that heat is conducted away and the surface you are touching doesn't warm up so much. 

Think about the difference between picking up a piece of wood and picking up a piece of metal with a bare hand on a cold day.  (Or - the other way around - how you can easily burn your fingers on a grill tray when you make some toast, but you can handle the toast with no problem at all.)

That’s not your body temperature. That’s how you feel. You can feel hot or cold but your body temperature is tightly regulated. 
 

Usualy it’s a circulation thing as you point out in your next post. Getting your muscles moving will increase your blood flow and ‘warm you up’.

There are two ways she could be colder than room temperature:

- Your room is really hot, over about 37°C

- She has been somewhere colder than your room in the last minute or so, and her skin hasn't heated up yet

Her body will be regulating its temperature to about 37°C, and being alive generates heat. Even if she was dead, she wouldn't cool below the surrounding temperature (to any significant amount - evaporation can cause a little cooling locally).

She can, however, feel colder than room temperature if her skin is colder than yours, as described above by deepsoup - you exchange heat quicker with skin than with still air.

Get a thermometer and check her skin temperature. It won't be colder than normal room temperature.

Since there's not much else to be doing today, I've just been experimenting with an infra-red thermometer. It says the inside of my cheek is 37.6°C, the middle of my forehead 34°C, the outside of my calves 31.2°C, the fingers of my mouse hand 22°C and the fingers of my non-mouse hand 25.6°C. The thermostat says the temperature of the room is about 18°C. 

Probably nothing to write to the Lancet about, but a clear difference between inside and outside, meaty and bony

Much more variation than I'd have expected - but it still isn't going to go below the surroundings (unless you hear your room another 20°C or so).

I'm mostly just impressed you have an IR thermometer, though!

There's a medical word for it.  Nesh.

I suffer badly from Reynauds. My core can be at the correct temp and my fingers below room temp. On a beach in Portugal, the temp was in the 30's but my hands were very cold to touch, even by someone just coming out of the sea. When I was a guinea pig on a medical research project they found my fingers could be almost 2 degrees below ambient and 7 below my core temp. This for me is not a worry. When the reynauds kicks in I have no sense of feeling in my fingers. Try finding the sweetspot on a small hold when you can feel bugger all!

I still don't understand how this can be possible

I do understand deepsoup's point above that it's possible for things to feel colder than the surrounding environment, but I don't get how the can objectively BE colder than their environment.

They are my fingers and I have no bloody idea. I only wish I did.

There is to be some research soon on the subject according to the guys on the project I was on. (Almost certainly on hold for sometime now!) Their associates used me as part of the preliminary input to designing the study. They used very sensitive contact thermometers and also infra-red photography. I asked if it was surface only and they said that it appeared to be full thickness. It may require thermo-sensors implanted deep in the fingers to sense surface to full depth temp ranges. They were not doing this on the preliminary research. I will be a willing volunteer when it starts. When/if I ever find out I will report it back on here. 

Long term, neither do I.  (In the absence of sweating obviously - body temperature can be maintained at below ambient temperature in a hot environment, a necessary survival trait for almost all of the homo sapiens that have ever lived.)

I get Reynauds too and often have cold fingers and toes at the most illogical times.  (Sometimes with the classic sharp line delineation between warm rosy pink skin and cold dead-looking waxy yellow skin.)  Even when extremities feel frozen solid I don't believe for a second that the temperature of my skin is below the ambient temperature of the room unless I've not long since come in from a cooler environment.  I think the overwhelmingly most likely cause of a reading that says otherwise would have to be experimental error.

It's not possible. The hand might feel really cold but will not be below room temp. 

Latent heat of evaporation. It’s how fridges work. As water evaporates from your hands it takes energy from them. 
 

Your fingers are then technically cooling the room.