The main difference
between cold weather and warm weather sniping is that the elements
in a cold situation can kill you just as fast as an armed enemy. When
confronted with the possibility of having to spend many hours outdoors
in these elements, we must consider not only comfort levels, but also
survival itself.
Temperature
is a measure of the heat of a substance. When your local meteorologist
tells you how warm or cold it is going to be outside, he or she is
generally referring to the temperature of the air close to the surface
of the Earth. But temperature alone will not tell you how cold you'll
feel when you get outsideespecially if there is a wind blowing!
Any warm object,
like a human being, will lose heat when it is exposed to cold air.
The greater the wind speed, the faster the object will lose heat. The
difference between people and inanimate objects is that we feel or
sense the heat loss. A temperature we feel is called a sensible temperature.
Maybe you've noticed that some days feel colder than others do when
there is a strong wind blowing, even if the temperatures are the same.
This phenomenon is known as wind chill. To estimate the heat loss based
on temperature and wind speeds, we use the Wind Chill Index. Wind chill
is referred to as an equivalent or sensible temperature, since it is
not an actual temperature.
The Wind Chill Index
is based on an equation first proposed in 1939 by Paul Siple, a famous
geographer, polar explorer, and an authority on Antarctica. In the
1940s, he and fellow Antarctic explorer Charles F. Passel conducted
experiments on the amount of time it took for water to freeze in a
plastic cylinder while exposed to the elements. They discovered that
the time it took for the water to freeze depended on the initial temperature
of the water, the outside air temperature, and the speed of the wind.
This was the original formula:
The US National Weather Service
uses the following formula to calculate wind chill:
WC = 91.4 -
(0.474677 - 0.020425 * V + 0.303107 * SQRT(V)) * (91.4 -T)
|
where: |
WC = Wind Chill Index
V = wind speed (mph)
T = temperature (° F) |
The wind chill
factor, which only affects humans and animals, causes the air to feel colder
than it really is. This helps us to understand how cold it feels
outside! Moving air carries heat away from the body more effectively
than air that is not moving. If there is no wind, the heat radiating
from a person's body will stay near the body and warm the air around
it. Therefore, the wind chill is simply a means of describing the
effect of the movement of air on the heat loss of a person's body.
Let's face it,
the weather strongly influences how we plan our operations and what
we wear! If it is raining, we wear Gore-Tex or some other type of
rainproof clothing. If it's cold and snowing, we dress in extra layers
to keep warm and dry. If there is a strong wind blowing on a cold
winter's day, we will feel colder than if there is no wind at all.
Based on temperature and wind speed, wind chill is a good indicator
of how cold we feel outside and allows us to make better decisions
to help avoid cold-weather dangers.
Prevention is
always the key! To protect yourself from any cold-weather danger,
always dress appropriately. If your meteorologist says to expect
an extremely low Wind Chill Index, don't go outside in shorts! Be
careful to remove wet clothing quickly and exchange it for dry garments.
Protect your extremities! Fingers, noses, toes, and ears are usually
the most susceptible areas to cold-weather injuries. Wear gloves,
warm socks that will not cause excessive sweating, and a hat or scarf.
Table of Wind-chill
Values: English Units
But why should
we care about wind chill? Well, a lower wind chill can increase the
rate at which certain cold-weather dangers, such as frostbite and
hypothermia, can develop. There are precautions that we can take
to avoid them when outside in extreme weather, such as wearing proper
clothing and using appropriate equipment. You can also check yourself
regularly for wet or cold areas on your body while outside in extreme
weather or use the buddy system to look for signs of danger and rewarm
body parts as needed. Check out our "Cold Weather Dangers" section
below to learn more about these conditions, the precautions you can
take to avoid them, and what the symptoms are!
So what are these
cold-weather dangers? One of them is hypothermia. This is
a condition where the core body temperature decreases to a level
at which normal muscle and brain functions are impaired. Any prolonged
exposure to temperatures less than 98.6 degrees can be linked to
hypothermia! Here are some of the conditions that can lead to hypothermia:
- Cold temperatures
- Wetness
- Improper dress/equipment
- Alcohol intake
- Poor food
intake
The severity of
hypothermia can vary, depending on how low the core body temperature
gets. There are specific signs and symptoms to look for. The condition
worsens as the core body temperature lowers.
Mild Hypothermia (core
body temperature ranges from 99-95 degrees Fahrenheit):
- Involuntary
shivering
- Inability
to perform complex motor functions (such as skiing, shooting)
Moderate Hypothermia (core
body temperature ranges from 95-90 degrees Fahrenheit):
- Slurred speech
- Violent shivering
- Dazed consciousness
- Irrational
behavior (for example, the person may begin undressing and is
unaware of being cold)
- Loss of fine
motor coordination
Severe Hypothermia (core
body temperature ranges from 90-75 degrees Fahrenheit):
- Pupils are
dilated
- Skin is pale
- Pulse rate
decreases
- Muscle rigidity
develops
- Shivering
occurs in waves, it is violent and then pauses; the pauses eventually
grow longer and longer until shivering ceases
- Person falls
to the ground and cannot walk; may curl into a fetal position
to conserve heat
- Person loses
consciousness, heartbeat and respiration are erratic
- Cardiac and
respiratory failure, then death
It is important
to be able to recognize the symptoms of hypothermia before it is
too late. To determine whether someone is suffering from hypothermia,
ask the person questions that require higher reasoning skills. For
example, someone who is hypothermic will probably be unable to count
backward by sixes from 100. Shivering that can be stopped voluntarily
is probably an indication of mild hypothermia. If you suspect severe
hypothermia and the person is curled into the fetal position, pull
back on one arm. If the arm curls back up, the person is still alive,
but in need of immediate medical treatment.
Now that you've
learned a little about the symptoms of hypothermia, you need to know
how to treat it. The most important things to remember are to reduce
heat loss, add fuel and fluids, and add heat.
To Treat Mild
to Moderate Hypothermia:
Add layers
of dry clothing.
Increase physical
activity.
Find shelter.
Keep the hypothermic
person fed and hydrated. Carbohydrates, with five calories per
gram, are released quickly in the bloodstream, creating a momentary
heat surge. Proteins, with four calories per gram, and fats,
containing nine calories per gram, are slowly released into the
bloodstream. These types of food supply a heat source over a
longer period of time. Hot liquids and sugars are also good.
Avoid caffeine, tobacco/nicotine, and alcohol.
Add heat (light
a fire or use some other external heat source). Try body-to-body
contact (the hypothermic person should be in dry clothing, in
a sleeping bag, and the normothermic person should be in dry,
lightweight clothing).
To Treat
Severe Hypothermia:
Try a hypothermia
wrap. Be sure that the hypothermic person is dry and has a layer
of clothing to minimize sweating. Use multiple sleeping bags,
wool blankets, wool clothing, and an aluminum "space" blanket
to create at least four inches of insulation around the person,
especially between the person and the ground. Wrap this entire
ensemble in plastic to prevent wind or water intrusion.
Keep the hypothermic
person hydrated and fueled. A severely hypothermic person will
be unable to digest solid food because the stomach may have shut
down. Try warm sugar-water or diluted Jell-O.
The hypothermic
person will have to urinate from cold diuresis; a full bladder
can mean additional heat loss. Urinating will conserve some heat.
You will have to help the hypothermic person do this. Be careful
to wrap him/her back up tightly in the hypothermia wrap when
finished.
Add heat using
chemical heat packs, hot water bottles, warm rocks, or compresses.
Rescue breathing for the severely hypothermic person can increase
oxygen and provide internal heat.
It is important
not to rewarm the peripheral areas of any hypothermic victim! The
core area of the body should be rewarmed to prevent a situation called
afterdrop. Afterdrop can occur when very cold blood from a peripheral
area, such as the legs or arms, returns to the core of the body and
lowers the core temperature even further! This blood may be acetic,
as well, and letting it return to the core of the body can cause
cardiac arrhythmia and death.
Although a hypothermic
victim may exhibit all the signs of being clinically dead, such as
blue skin, fixed and dilated pupils, rigid muscles, and no noticeable
breathing, he or she may still be alive! The victim may be in a state
of "metabolic icebox," which occurs when the body temperature
drops to 86 degrees Fahrenheit or lower. If this is the case, it
is necessary to rewarm the victim and possibly perform CPR. DO NOT
perform CPR if a heartbeat is detectable, even at a rate of 2-3 beats
per minute. The heart is beating slowly, but it is still distributing
blood. The heart is hyperexcitable during severe hypothermia and
stimulation through CPR, or simply moving a victim, can cause fibrillation
leading to death.
Frostnip
and Frostbite
Frostnip
and frostbite are two types of cold injuries that are related to
the amount of heat circulating to peripheral areas of the body. These
include fingers, toes, ears, and the nose. Frostnip is essentially
the freezing of the top layers of skin; it is generally reversible.
Frostbite is more severe because freezing occurs through all layers
of skin, and muscle and tissue may freeze. Both are serious conditions.
Preventative measures should be taken whenever there is potential
danger.
So, what are the
factors that can lead to these conditions? Well, some of them are:
- Wind chill
- Wetness
- Lack of insulation
- Dehydration
- Constrictive
clothing
- Exposed skin
- Body type
Alcohol, nicotine,
and caffeine can also influence your susceptibility to frostnip and
frostbite. Alcohol can increase heat loss by increasing surface blood
flow. Caffeine causes water loss and can speed dehydration. Nicotine
can decrease the blood flow to peripheral body parts and increase
your chances of getting frostnip or frostbite. What are some of the
signs of frostnip and frostbite? And how do you treat these conditions?
Frostnip can cause
the skin to look very white and waxy. The top layers of skin can
feel hard, but the tissue underneath will still feel soft. There
may be some numbness associated with frostnip. To treat frostnip,
gently warm the affected area by placing it against a warm body part
(your own or another person's), or by blowing warm air on the affected
area.
Frostbite can
cause the skin to look white and feel hard all the way through the
skin layers. Numbness is also associated with this condition. If
only a small area on the body is affected, frostbite can be treated
as frostnip. However, if there is deep frostbite, such as when muscle
or bone freezes, it becomes a much more serious condition that requires
further treatment. Immerse the affected body part in a water bath
of 105-110 degrees Fahrenheit. Dry heat is not effective. It is important
that the water temperature doesn't exceed 110 degrees Fahrenheit
because further damage may occur. It is also important that the temperature
of the water is continuously monitored, since it will cool, and warm
water is added as needed. Do not run water directly over the affected
area. The water bath should last about 25-40 minutes. Once rewarmed
by the water bath, the area should be soft and color and feeling
should return. Once the area is rewarmed, it should be wrapped and
protected from movement and cold. The rewarmed body part cannot be
used again once rewarmed. Also, it is crucial that the body part
be protected from refreezing. If you cannot protect the body part
from refreezing once it is warmed, then do not rewarm
it. Once tissue is frozen, the bulk of the damage has already been
done. Refreezing frostbitten tissue can cause extensive damage and
may lead to tissue loss.
Please note: NEVER rub
skin that is affected by frostnip or frostbite. Ice crystals form
within cells during the freezing of tissue. Rubbing affected skin
can cause the destruction of cells as they are torn from the ice
crystals.
Clothing
Considerations
The old Army Ranger
adage "Travel Light, Freeze at Night" just does not cut
it for extreme weather conditions. You may just kill yourself and
your team if you don't plan your equipment list for the extreme.
It matters little if you are a military sniper on extended operations,
a law enforcement sniper deployed on a hostage barricade situation
for several hours or a hunter out to put food on the table. The conditions
that have been discussed earlier can, and will kill you in a very
short amount of time.
The first thing
we must do is understand the design principles of current cold weather
clothing. They are: Insulate-Insulation material reduces the
amount of heat loss. By regulating the amount of insulation, an individual
can regulate the amount of heat lost or retained. Layer-Several
layers of clothing provide more insulation and movement than one
heavy garment, even if the heavy garment is as thick as the combined
layers. Air pockets trapped between the layers provide insulation
and warmth. Ventilation-Ventilation helps maintain a comfortable
body temperature by allowing excess heat and moisture to escape.
With the principles
in mind, the key to keeping warm in winter climates is the word C-O-L-D.
Keep clothing
clean. Dirty clothes are cold clothes. Dirt and grease clog the air
spaces in clothing and reduce insulation. Avoid overheating. Select
comfortable clothing and don't overdress. In cold weather, it is
better to be a little cool rather than risk being overheated. Wear
it loose. All items of your cold weather clothing should be large
enough to allow wearing of the appropriate number of layers. If no
loose fitting layers exist, then you will have less insulation to
keep you warm. Keep it dry. It is important to keep clothing dry,
since wet clothing conducts heat away from the body more quickly
than dry clothing. Moisture soaks into the clothing from two directions:
the inside and the outside. From the outside you must guard against
melting snow; from the inside you must guard against sweating. Brush
snow and frost from clothing before entering any heated shelter or
vehicle, and avoid overheating by venting the clothing when needed.
The current issue
(US Military) cold weather clothing system allows the user to layer
and vent as needed. With the addition of Gore-Tex and Polypropylene,
we now have a lighter weight system that keeps us warmer and dryer.
First
Layer
Polypro long
underwear is worn as the sole undergarment next to the skin. They
are designed to draw moisture away from the skin, thereby reducing
conductive heat loss. You must make sure that no other clothing item
is placed between these items and your skin. Socks should be worn
with an inner layer of nylon and then covered with a wool product.
Second
Layer
The second layer
contains a synthetic fiber pile shirt and polyester batting trouser
liners. Both provide needed insulation. The shirt is designed to
dry quickly if it becomes wet and provides a high degree of insulation.
It should not be worn as an outer garment in wet or windy conditions,
since the loose weave provides little protection against wind chill.
If the shirt is wet the insulation value is reduced.
The trouser liners
are designed to be worn during little or no activity. They should
not be worn during heavy activity such as skiing or snowshoeing.
Third
Layer
This consists
of polyester batting field jacket liner and field trousers. The jacket
liner should only be used for extra insulation 
during periods of
little activity. This 
liner
is designed to be used as a separate jacket; it should not be attached
to the parka. The field trousers provide a durable wind-resistant,
water-repellent layer to protect the insulating underpants and trouser
liner. We must now add a good pair of insulated boots. The GI issue
just won't cut it here. For periods when you must keep moving, I
prefer a lighter insulated boot similar to the newest hunting boots
that are offered. For the times when I must stay in a position for
long periods of time, I like the heavier style of boots by Rocky
or Sorel. They have a rubber sole and lower and a leather upper,
which is insulated with ½ to ¾ of an inch of heavy
batting.
Fourth
Layer
Windproof, waterproof
parka and trousers make up this layer. Both are used as a shell to
protect 
the
other three layers.The parka should be the outer garment,
which
is always worn when doing any activity outside a shelter. It is waterproof,
yet the fabric is breathable so that body moisture can escape. The
hood is designed to give full protection from wind and snow and does
not prevent you from seeing the area around you. It has underarm
zippers to allow air to circulate during heavy activity. The trousers
are made of the same material as the parka and are very warm. They
should be worn only when necessary to prevent the field trousers
from becoming wet.
The last item would
be gloves. If my hands are cold, my whole body seems to
feel
thesame. For this reason, quality gloves are as important to me as
warm, dry boots. My favorite pair is from Cabelas and is made to
military specifications. These gloves are constructed of 330-denier
Cordura® Ambush Cloth nylon with tough leather on the palm,
finger fronts and index finger to stand up to tough use. 100% waterproof,
breathable Gore-Tex insert and 200-gram Thinsulate insulation protect
you from the cold, 
wet
weather. Hydrofil® nylon lining helps wick perspiration from
the hand for added comfort.
Fifth layer
Camouflage
overwhites make up this layer. Although it adds some insulating value,
it is concealment that you are after here. If the area you are working
in has sporadic snow cover, you should add some earth tones to the
overwhites with spray paint.
Additional Information on extreme
outdoor clothing can be obtained by contacting:
