Cold regions include arctic and subarctic areas, and areas immediately adjoining them. About 48 percent of the Northern hemisphere’s total land mass is a cold region, due to the influence and range of air temperatures. Ocean currents affect cold weather and cause large areas normally included in the temperate zone to fall within the cold regions during winter periods. Elevation also has a marked effect on defining cold regions. Within the cold weather regions, you may face two types of cold weather environments-wet or dry. Knowing which environment your area of operation (AO) falls in will affect planning and execution of a cold weather operation.
4-37. The two types of arctic climates are wet-cold and dry-cold.
WET-COLD WEATHER ENVIRONMENTS
4-38. Wet-cold weather conditions exist when the average temperature in a 24-hour period is 14º F (-10º C) or above. Characteristics of this condition include freezing temperatures at night and slightly warmer temperatures during the day. Although temperatures in a wet-cold environment are warmer than those in a dry-cold environment, the terrain is usually very sloppy due to slush and mud. Protect yourself from the wet ground, freezing rain, and wet snow.
DRY-COLD WEATHER ENVIRONMENTS
4-39. Dry-cold weather conditions exist when the average temperature in a 24-hour period remains below 14º F (-10º C). Even though these temperatures are much lower than normal, you can avoid freezing and thawing. In temperatures down to -76º F (-60º C), wear extra layers of inner clothing. Wind and low temperatures are an extremely hazardous combination.
4-40. Success in the arctic begins with preparedness:
4-41. Wind chill increases the hazards in cold regions. It is the effect of moving air on exposed flesh. For example, with a 15 knot (27.8 kmph) wind and a temperature of -14º F (-10º C), the equivalent wind chill temperature is -9º F (-23 degrees C). Remember, even when no wind is blowing, your own movement, such as during skiing, running, creates “apparent” wind, will create the equivalent wind by skiing, running, being towed on skis behind a vehicle, or working around aircraft that produce windblasts.
4-42. Soldiers will find it almost impossible to travel in deep snow without snowshoes or skis. Traveling by foot leaves a well-marked trail for pursuers to follow. If you must travel in deep snow, avoid snow-covered streams. The snow, which acts as an insulator, may have prevented ice from forming over the water. In hilly terrain, avoid areas where avalanches appear possible. On ridges, snow gathers on the lee side in overhanging piles called cornices. These often extend far out from the ridge and may break loose if stepped on.
4-43. Many sources of water exist in the arctic and subarctic. Your location and the season of the year will determine where and how you obtain water. Water sources in arctic and subarctic regions are more sanitary than in other regions due to the climatic and environmental conditions. However, always purify water before drinking it. During the summer months, the best natural sources of water are freshwater lakes, streams, ponds, rivers, and springs. Water from ponds or lakes may be slightly stagnant but still usable. Running water in streams, rivers, and bubbling springs is usually fresh and suitable for drinking.