malmo wrote:
kmaclam wrote:Huh??? That's fully 20 degrees warmer than optimal temp of 49.
I don't think you're going to get this, I don't know if you are even capable of understanding what should be junior high science, but I'll try.
Temperature is not a fungible metric. 69 degrees here is not the same as 69 degrees there, or over there. That seemingly precise number isn't so precise at all. When the weather service reports temperature it is an "in the shade" measurement. 69 in the shade is quite different than 69 in the yard with the sun directly overhead, which is different than 69 on a concrete sidewalk, and even more different than 69 on an asphalt street. You already know this. The ground level ambient temperature on a sunny day is going to be much higher than that 69 degrees that the weather service is reporting. If is is cloudy then 69 degrees doesn't feel bad -- even at noon.
The Sun's altitude makes a huge difference in the ground level ambient temperature vs the reported temperature. At sunrise the Sun's radiant energy hasn't yet had time to amplify at ground level, so 69 is 69, just as the weather service told you. But at noon the ambient temperatures on a sunny day will probably be 20 degrees higher.
Boston Marathon used to start at noon. The NYC Marathon used to start at 10:30. This went on for decades until the slow-learning Einstein's finally realized that the runners were screwed on sunny days, so they eventually caught on and moved their starting times earlier. Now it's not unusual to see 8 am starting times. Berlin is 9am. Dubai is 6:30, a half hour before sunrise.
Running a marathon at 6:30 in Dubai, temperature 69, dew point 59 is not a problem at all, as was clearly demonstrated. Understand yet?
Remember the Golden League 5000 at Doha has been won in 12:50 when it was 90 degrees on the track. How come? 90 at 9pm isn't the same as 90 at noon...that's how.
Correct.
Add to that that the sun directly on your head causes it to sweat and lose water. Dehydration is a big factor.
The ambient temperature could be fine, but the sun's rays directly on your skull for a couple hours will make you heat up a lot more than the temperature suggests.
Dubai was cloudy.