The question pretty much sums it up. How TF is the asphalt 20-40° hotter than the air when it’s super hot?
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Heat transfers in 3 ways:
Conduction — Substance touching substance. Heat transfers from the hotter substance to the cooler substance depending on the difference in temperature and heat transfer properties of the substances.
Convection — Substance touching liquid/gas substance. Heat transfers to/from the liquid/gas, but, because it’s a liquid/gas and hot liquid/gases rise while cooler liquid/gases fall, it causes a flow where the liquid/gas rises/sinks and is replaced by more liquid/gas which then itself gets heated/cooled — and the cycle continues.
Radiation — Substance absorbing/releasing electromagnetic waves. Does not require a medium (can happen in a vacuum) and travels at the speed of light.
The heat transfer you’re thinking about is the first 2. Both of these have bounded limit of temperature change. If Substance A is hotter than Substance B, there’s no way for Substance A to cool down to below Substance B purely from contact and there’s no way for Substance B to get hotter than Substance A purely from contact.
However, no such limitation exists for heat transferred by radiation. If you hit a substance with heat radiation, and if you had a theoretical substance that didn’t give off any heat radiation of its own and had no way to dissipate that heat via conduction/convection, then the temperature of the substance would rise indefinitely.
This is part of the reason why a 60-70 degree day might feel like 80-90 in the sun. The 60-70 degrees reported by weather agencies is taken away from solar radiation (ie from a shaded area). But when you’re outside, you’re feeling the 60-70 degree ambient temperature PLUS whatever heat radiation your body is absorbing from the sun.
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