Saturday, January 14, 2012

Cold Weather Astronomy: Be Prepared!

In my prior article I discussed ways of staying warm and safe while observing in the cold by controlling your location and taking advantage of what's nearby. In this article I'll discuss personal preparation and protection from the cold.

Fashion Sense and Sensibility

Obviously clothing is an important part of staying warm when out stargazing in winter. Having the right clothes for the conditions is critical. When it's really cold, it's not something you can fake easily with substitutions. Proper winter wear that protects both your core temperature and your extremities is critical.

Humidity Good and Bad

Even though the humidity high in the sky is very low, thanks to the cold conditions, the humidity levels at ground level can be quite different. If it's at all damp where you are, this can make it feel far colder than the temperature would suggest. Also, as the evening cools this dampness can condense on you and freeze as well. So any clothing used must protect against moisture.

While humidity outside your clothes can be a problem, inside your clothing it's part of keeping yourself warm. Clothing that helps trap your body's moisture to some degree helps keep you warm. The colder it is, the more your clothing should confine the moisture.

The Layered Look

Layers of clothing are important, both to provide redundant levels of protection from the cold and to serve different purposes. Clothing worn near the skin should be porous and absorbent to keep moisture from collecting on the skin, which can chill. It also allows the warm air trapped within your outer clothing to circulate some to better distribute your body's heat.

The next layer out should be chosen for warmth, and should also breath some. Wools and acrylics are good choices, as they will keep you warm no matter what the level of moisture.

The outer layer should prevent wind from getting in and your body's heat and moisture from getting out.

Easily Freezable Bits
Hands, feet, ears, and other outer parts of your body deserve special attention. They freeze easily, and are easier to forget when a particularly nice bit of galactic detail swims into view.

Heated socks and gloves are available, and heated hats. Some use batteries and heating elements, others use chemical packs to generate warmth. In my case I've found aluminized clothing to work just as well. I have aluminized socks and glove liners that I wear in cold weather. They work so well they literally feel as if they are electrically heated.

For example, I usually wear the following on my feet:
  • Inner cotton socks

  • Acrylic knee-high socks

  • Aluminized socks

  • Outer wool or thick cotton socks

I have a loose pair of older leather boots that I wear in winter to accommodate these layers of socks.

On my head I wear a balaclava under a heavy winter hat.

On my hands I wear a pair of cotton-lined aluminized gloves, with a pair of leather "police inspection" gloves outside of them. These aren't quite enough to protect my hands on the coldest nights, but I use these because it still leaves me enough dexterity to handle eyepieces and focusers. I put my hands inside heavy pockets when I'm not actually handling things, or use an outer pair of heavy mittens if I'm not going to use the pockets or if the pockets just don't stay warm enough.

Internal Preparation

Before going out into the cold, it's important to be well fed. Don't go out hungry, it leaves your body with insufficient reserves to keep you warm, and keep you alert enough to notice if you're getting too cold to be safe.

I usually plan a warm meal with a warm drink before going out. I also keep something warm to drink, and a high calorie snack available for observing breaks. If at all possible, these breaks should be taken in a warm place.

Breaks and Self-Inspections
Plan to have breaks in your observing sessions. They should be long enough to let you warm up completely. You need to be able to tell if parts of you are getting too cold, or if you're having trouble making decisions clearly. I do a bit of observation logging during my warm-up sessions to give me something to do while warming.

When outside, and when inside, perform a self-inspection to see if any part of yourself is getting cold and numb. Frostbite is not a necessary part of astronomy. Check your fingers and toes for flexibility and feeling. Check your ears, nose, chin, scalp, elbows and knees. Poke your calves and forearms while you're at it. Blink your eyes and make sure any cloudiness blinks away. Touch any exposed skin to make sure it's still there.

Two Ways to Err
It's possible to make mistakes in either of two ways: being too gung-ho and ending up regretting an observing session that goes too long or that you get too cold. It's also possible to miss out on some of the best observing time of the year by being too timid and hiding from the cold when the proper location and dress would be all it takes to have an enjoyable time under the sky.

Don't miss out on winter observing, and don't over-do it, either!

Plus, if you have any personal tips or tricks you use, please share them in the comments.

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