Comment by bungie4 | Hacker News Reader

Comment by bungie4 | Hacker News Reader

It was my undertanding that the Bedouin wore full body clothes to SLOW evaporation. In the desert, your sweat evaporates to fast (because of the near 0 ambient humidity) not giving it enough time to pull heat out of your body. Thus, making you even hotter.

I've experienced this very thing riding a motorcycle through Arizona. Man, it takes some real willpower, but gearing up is what is required when the temps go over about 85F. Just don't stop!

Tip. On a motorcycle, wet your shirt. Zip up your coat. Unzip your wrist cuffs. This slows down the airflow giving time for the water to evaporate and cool you, while providing an intake and exhaust. You will be amazed at how well this works. You can actually regulate the temperature (air flow) by opening or closing the zipper by your neck.

This will not work in areas with high humidity like the deep south.

Yes, while hiking in dry hot climates I wear long sleeves and long pants, partly to keep the sun off but it also improves your water economy. Less water will be lost and you don't need to drink as much.

I have a Cordura AFT riding jacket that is fully armored but feels like wearing a T-shirt in terms of airflow. Worth every penny.

I think they wear it to protect their skin from the sun first and foremost, and the choice of fabric is then designed to alllow for good air circulation and evaporation. At least, that’s the point during the day, but it’s worth remembering that it can and does get damned cold at night, and the same garment works well then too. From a purely physical standpoint, If the sweat is evaporating from your skin, it is that action which moves heat, not the length of time the liquid stays on your skin. It’s a matter of the enthalpy of evaporation, so a high rate of evaporation can only be a good thing. A good light fabric to protect you from sunstroke and dust, breathable to allow for (ideally moderate) perspiration to evaporate rather than drench the fabric, and then the whole thing works to keep you warm at night. If you’re constantly on the move, it’s pretty efficient!

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