Checking my phone for the temperature, I see that its currently 91 degrees but it feels like 99. Got me wondering how thermometers work/how they came to be and how they calculate “what it feels like.”
In: Technology
Generally thermometers can have a couple of mechanisms.
The “normal” analog thermometers beside the window you might know have a liquid (mercury or an ethanol solution) which expands when heating up and therefore rising up.
Digital Thermometers often have resistance based systems. There a current flows through some sort of cable, which changes according to the temperature. This cable is put in the medium you want to measure.
Your phone however doesn’t measure the temperature directly. It gets its data from weather stations in your area.
An alternative measurement of temperature is the measurement of infrared radiation (used by satellites or heat cameras). Because everything gives away radiation (which is essentially light but with a different wavelenght – like so red you can’t see it anymore), and the energy of this radiation depends on the temperature of the body you are able to calculate it back. It is essentially what you feel if you are near somebody and you fell there warmth.
How the “feeled temperature” is determined I am not sure, but I would guess that factors like wind go into that calculation. You can imagine that your body (around 37 °C/100 °F/310 K) heats up the air near you. If this air is blown away you feel colder as the heat from your skin is transfered to the new air (if its colder). If the air stays around you, you will feel warmer. You can feel this effect when its windy or when running.
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