Assuming no wind 60 degrees outside feels decently warm however when the ac is set to 60 degrees I feel like I need a jacket.
In: 3186
For comfort and survival it matters more that we can shed heat generated by metabolism to the environment. If it’s humid, sweat can’t evaporate as well. If the air is moving, each bit of air heated by the body gets replaced. Sunshine can directly add heat.
At least you touched on the more important aspect in the question: why does it *feel* warmer or cooler. Human perception is not a thermometer. Things feel warm or cool depending on the heat transfer rate, like for 50F air vs 50F water.
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Outdoor temps are the air temp, so in the shade. But outside, especially if it’s 60, you’ll walk in the sun, which will feel warmer. You are also more likely to moving outside which will also make you warmer.
Outside Temperatures are taken in the shade, so sunny and 60 isn’t actually what 60 degrees feels like.
People have hit on some things here, but not the most important thing. What we call heat is not a single thing. There are three different types of heat energy that have different properties. Inside, we almost exclusively have access to the least efficient type (IR-C). Outside in the sun, we experience almost entirely IR-A and IR-B, both of which are much more efficient at penetrating the skin, so it heats us much more deeply. As a result, we feel much warmer in the same temperature in sunlight than we do indoors.
* Solar radiation creates additional heat on your skin that is not measured by most thermometers.
* When you’re outside you’re probably moving around more, which requires energy from your body. Higher metabolism has your body generating more heat.
* No wind isn’t helping here as that reduces the overall cooling power the ambient air has by keeping you in contact with already warm air (from the heat generated via the above two processes) for longer, reducing heat transfer
We are talking g about two different ways of interpreting temperature. First there’s ambient vs. Radiant heat. Ambient heat is room temperature and temperature in the shade. Radiant heat is heat temperatures coming directly from the sun, coming off hot assault, or a burning fire. While the ambient temperature may read 60* outside, in direct sunlight walking over a black tarmac you will be subjected to different temperatures.
Other factors that are present out side vs inside would be relative humidity. When an AC is running inside, a side effect is that moisture is being drawn out of the air. So the experienced 60* in doors will be at a lower humidity level than what might be out doors. Generally we experience higher humidity as stuffy, hard to breathe, and more difficult to cool down. In high humidity situations, the ambient temperature is more easily applied to the body, because heat transfers better through moist air than dry air. It’s why steaming vegetables is much faster at a lower temperature than roasting them in the oven.
Finnally we have the other experienced phenomena that may lead to the perception that it is cooler inside at 60* than outside. This would be our bodies’ instead ability to acclimate to different surrounding. Acclimating is really nothing more than our brains’ perception of hot and cold. Considder this, spend all day in an ice house, getting yourself chilled to the bone. Go inside where there’s a room temperature bath. Put yourself in that bath and you’ll experience the sensation of being boiled alive.
Conversely, spend all day outside in 110* heat, under direct sun light with 100% humidity, sweating a storm from all over your body. Go inside and place yourself in that same room temperature 60* bath…. you will feel yourself freezing to death, complete with shivers, chattering teeth, goosebumps, the whole proction.
But in reality, you aren’t actually experiencing either of these extremes. The temperature of the water is as it always was, a cool but comfortable 60*
The same can be said for indoor vs out door temperature. Stay inside where the ac may be blasting you all day, body cools down as a result, step outside where the air is now dead still, a little muggy, and even if the heat isn’t radiating, the contrast will be precieved as a marked shift in tempreture, even if the ambiants is also 60*
Humidity as others have said, but another big reason is radiative heat transfer.
Heat transfers to and from us in a few ways. Convection through the air is typically the most significant – air moves over and around your skin, and if it’s cooler than your skin it will remove heat, cooling you.
Radiation is another way heat is transferred. Radiative heat transfer is always happening. To keep it ELI5, all surfaces constantly radiate heat to some degree. Typically a hotter surface will transfer heat to a cooler surface. When you’re outside on a 60 degree day, the most significant source of radiative heat is the sun, but even in the shade this can be significant. The heat from the sun reflects off surfaces and heats you, and as the sun heats objects they begin to radiate heat to you as well.
Inside, if your AC is set to 60, the walls are probably also 60, so the net radiative heat is leaving you, cooling your skin.
The sum of these effects is the temperature it “feels.”
Humidity, moisture vapor in the air.
and “Heat Index” (aka “Feels Like”) can tell you what temperature it seems to be in human experience if you simply know the temperature and relative humidity level:
* ***https://www.wpc.ncep.noaa.gov/html/heatindex_equation.shtml***
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