OAUSA Net - August 16, 2018 - Keeping Cool Outdoors

[DaveK]

KEEPING COOL OUTDOORS

If you have listened to our nets, you know that we believe in "comfort camping." This is not to say that we hold comfort above all else, but when vehicle space permits and the cost is reasonable, then we most certainly give serious consideration to any new idea that pops up. Summer time, and the heat that naturally accompanies this season, keeps us on the constant prowl for a means to keep cool.

Paul, KK6DYO, being the skilled inventer he is, has a solution that might become a permanent part of your camping gear, especially when the temps start rising. Join us for a discussion of a most unique solution to hot summer nights (and days too!).

[KK6DYO]

I love being outdoors, specifically in the desert, but hate the limited seasons during the year. The desert is essentially off limits from mid-Spring through mid-Fall. Just too hot during Summer days, though the nights can be very comfortable.

For decades I've been trying to "stay cool outdoors". I've come up with a few things that sort of work, but no real solutions, other than to mostly avoid being outdoors during six months of the year.

I'm hoping that others have discovered techniques and practices that work for them, and are willing to share them as we together trying figure out how to stay cool outdoors.

The temperatures for Borrego Springs might be considered typical for a desert.

Borrego Springs, California average temperatures

Recent day's temperatures at Anza Borrego

While humans can acclimate to temperature extremes, we're mainly confined to a 10° range of comfortable temperatures, depending on humidity.

Badwater, Death Valley to Whitney Portal Ultramarathon

Comfort range: temperature v. humidity

Comfort.png (71.77 KiB) Viewed 636 times

One idea of comfort

I doubt one can stay truly cool, so perhaps this net should be called "How to Avoid Dying in the Desert". The following chart shows combinations of temperature and humidity that can lead to dangerous and possibly fatal heat injuries, which we'll look at in more detail later.


Comfort, discomfort, danger of heat injury

Heat index is a fairly complex calculation that uses temperature in the shade, and doesn't take solar radiation and air movement (wind velocity), critical to an overall comfort determination.

[KK6DYO]

https://en.wikipedia.org/wiki/Thermodynamics

First law of thermodynamics: The internal energy of an isolated system is constant.

You must transfer energy (heat) to become cooler.

Second law of thermodynamics: Heat cannot spontaneously flow from a colder location to a hotter location.

If it's hotter outside than you are, it's tough to get cool.

Ways to transfer heat

[KK6DYO]

Our primary mechanism for transferring heat is perspiration
2.6 million sweat glands on average

[KK6DYO]

Heat Index and Potential for Heat Injury
And note that heat index in calculated for the shade, not accounting for solar radiation

Heat Injury Symptoms and Treatments

Note that Heat Stroke is a medical emergency!

You must avoid heat injury by keeping cool

[KK6DYO]

Water


Sports Drinks

• Enhances absorption of fluid more than water alone
• Sugar content higher than body fluid so difficult to absorb

Caffeine

• Diuretic - can increase non-sweat water loss (urination)
• Can increase heart rate
• Can increase blood flow to skin

Alcohol

• Diuretic - can increase non-sweat water loss (urination)
• Inhibits hormone that regulated fluid balance
• Depresses hypothalmus which regulates body temperature
• Can increase blood flow to skin

[KK6DYO]

The risk of Sunburn has to do with the melanin in your skin. Dermatologists rank all of us in a skin pigment level depending on your melanin level. Melanin is the pigment in your hair, skin and eyes that give color. Those with lighter skin have less melanin than those with darker skin.

• Type I: Pale white skin – always burns, never tans
• Type II: White skin – Burns easily, tans minimally
• Type III: White skin – Burns minimally, tans easily
• Type IV: Light brown or olive skin – Burns minimally, tans easily
• Type V: Brown skin – Rarely burns, tans easily and darkly
• Type VI: Dark brown or black skin – Rarely burns, always tans, deeply pigmented

The Thobe
How hot does a thobe get?

Bedouins wearing black
Why do Bedouins wear black robes in hot deserts?

We report here that the amount of heat gained by a Bedouin exposed to the hot desert is the same whether he wears a black or a white robe. The additional heat absorbed by the black robe was lost before it reached the skin.

Sun Protection Factor (SPF) versus Ultraviolet Protection Factor (UPF)

SPF is for subscreen

Neutrogena UltraSheer Liquid SPF 70
Meateater - Wear Sunscreen

Ultraviolet radiation: UVA, UVB, UVC

UPF is for clothing

Clothing Material
Light color (reflective), breathable, wicking, light weight, loose
Cotton, polyester, or mix?
Virtually all of my "wicking" polyester is not breathable to uncomfortably sticks to my sweating body


Clothing Label

Shirt

Columbia Tamiami Shirt
UPF 40, 100% polyester, wicking, mesh-lined venting in back

Pants

And did you also want that in camoflage?


From Consumers Digest:

Sweat cools you when it evaporates from your skin’s surface, and ... you might cool down less if the evaporation happens on the outside of the fabric instead of on your skin, Taylor says. Consequently, a shirt could cool you less than bare skin does.
...
Gavin published studies ... that reported on how different types of clothing influence the body’s capability to keep cool in the heat. None of his research found any discernible effect regardless of fabric types.

Though obviously, wearing clothing with a high UPF rating will protect you from solar radiation which could be the major factor in how cool your skin is.

http://www.consumersdigest.com/special- ... l/view-all

[KK6DYO]

Wide brim, light color, light weight, well ventilated, wicking sweatband, chin strap, dark underbrim, stylish!

Stetson Coffee Tab Outdoor Hat

Stetson Costner Vented Jute Outdoor Hat

Dorfman Pacific Soaker

Tilley AIRFLO

Shemagh

Adam's Headwear Extreme Condition Hat

Vaqueros

Kool Breeze

Ghutra
5 Ways to Wear Your Ghutra

Mission Tech Knit Hoodie

Sun Umbrella

[KK6DYO]

Merrell Moab 2 Ventilator

Keen Newport Hydro

Socks
Duluth Trading

[KK6DYO]

• Sunlight (UV) protection - polycarbonate blocks 99.9%
• Safety - especially if shooting (ANSI Z87.1)
• Scratch resistance
• No distortion
• Light weight
• Anti-fog
• Comfort
• Polarized?
• Prescription?
• Stylish!

Dark Smoke Lens Shooting Glasses $7.23