The sun adds 1000 watts per square meter, and black body radiation is the fourth power of temperature difference. If you're heating the skin say 5000 watts per

The sun adds 1000 watts per square meter, and black body radiation is the fourth power of temperature difference. If you're heating the skin say 5000 watts per square meter due to friction or compression, then the 1000 watts from the sun isn't bad. But if it's only say 500 watts, well, then the sun dominates. They operated at different speeds and altitudes so it's not entirely surprising to me that they had different strategies.