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Can someone explain why 50 F in the sun feels so much warmer than 55 F under cloudy skies, in the shade, or after dark even with no wind and why there is no such thing as "sun warmth factor" to take this in account?
Can someone explain why 50 F in the sun feels so much warmer than 55 F under cloudy skies, in the shade, or after dark even with no wind and why there is no such thing as "sun warmth factor" to take this in account?
Your asking us why the yellow ball in the sky is warm?
There is the heat index and apparent temp which factors just that. but the criteria is higher because 55 degrees is not considered warm when you need the heat on with that temp.
Sun's rays hit your skin, making it feel warmer than it is. If you ever get the chance, come to the Mid-Atlantic states in winter when it's sunny and around freezing. Sit in your car without your jacket on, and you start to feel the sun's warmth on your skin
I'm glad someone else said this because I didn't want to sound stupid. I agree because no matter how cold it is, the sun will make it feel at least 10 degrees warmer than the actual temperature. If it's in 30s with sunshine and no wind, it can actually feel a little warm.
Can someone explain why 50 F in the sun feels so much warmer than 55 F under cloudy skies, in the shade, or after dark even with no wind and why there is no such thing as "sun warmth factor" to take this in account?
Thanks for bringing this up. It is exactly what is happening here in NJ.
Yesterday it was 59 F with brilliant sunshine which felt quite warm. Most people at the university were wearing t shirts or tank tops with sunglasses & jeans like it was late summer.
Today it was actually warmer at 61 F, but with rain and wind. I saw very few people dressed up in such light summer like clothing (except myself, since I love the refreshing and damp 60 F air on my skin ).
Sunlight is not the only factor however, it also has to do with wind and humidity present. A calm 50 F day with brilliant sunshine and high humidity feels more like the mid 60's. However, a windy 50 F day with clouds and high humidity feels more like the low 40's. This is the conduction and convection component impacting how temperature feels.
Another additional factor to consider is that during midday, the sun is actually providing the maximum radiant energy to the ground, hence you tend to receive much more solar energy on your body and hence feel much warmer during this time of the day. By contrast, on a clear pitch dark night the ground is losing radiant energy which makes temperatures feel much colder than they actually are.
For more info, refer to the Bioheat Equation lecture, which is a complex partial differential equation. I love Solving PDE's and their qualitative analysis. Makes me so excited once I arrive at a solution. .
Your asking us why the yellow ball in the sky is warm?
There is the heat index and apparent temp which factors just that. but the criteria is higher because 55 degrees is not considered warm when you need the heat on with that temp.
I just noticed that around noon, it's around 55 here and it feels warm in the direct sun. Sun goes down around 5PM and it's around 60 around sunset. Yet, it feels cooler at sunset than in the direct sun at noon.
The weather here the last week or so has been much cloudier and wetter than the last 3-4 months.
Even though the published maximums are similar, days with sunshine feel considerably warmer. I guess temperatures are measured in the shade (correct me anyone if I am wrong) so presumably to create a standardised measure?
Sun angle also makes a difference. Sitting out in the sun in Miami at 85 degrees is different then sitting out in the sun in Chicago at the same temperature.
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