A low-temperature environment is a stressful one, where the temperature is consistently below the freezing point for water, 32°F (0°C).
Low temperature can change the state of metals, gases, liquids and solids, cause damage to organisms depending on length of exposure, and change the functionality of mechanized processes.
Cold temperature environments naturally occur in high altitude or high latitude areas. Because salt water freezes at a lower temperature than fresh water, cold temperature environments can occur at great depths or near the poles. Many salt water bodies within the Arctic and Antarctic circles have surface temperatures below 0°F (-18°C) at year end. This state provides a challenge to fishing or traversing those bodies of water and changes the biological makeup of those seas and oceans. In these areas precipitation only falls as snow or ice, reducing visibility and handicapping boats, buildings, and other manmade infrastructure.
Artificially created low temperature environments are commonly found where freezing cold is necessary for food storage, medical storage, scientific applications, and commercial or industrial uses. Typically, these cold environments are called freezers. Freezers remove the heat out of the freezer compartment by putting gas (R134A, R410A, or ammonia) into a compressor, which heats the gas, turning it into a liquid, and upon being forced through a small opening into coils under the freezer compartment, it evaporates back into a gas, taking the heat in the freezer compartment with it. In this cyclical process, the gas heats back up from absorbing the heat from the freezer compartment.
The prefix cryo means “the production of freezing cold.” For example, cryogenics is the branch of engineering and physics that covers low temperature, how to produce it, and how materials behave in the cold. There are many practical and scientific applications for freezing cold temperatures. Frozen foods, for example, can remain safe indefinitely (the U.S. Food and Drug Administration (FDA) maintains standards for food safety of frozen foods for taste and safety). In some instances local freezing is used as a medical application, as in freezing warts and cancer cells in order to remove them and other cryosurgical operations. Additional applications include freeze-drying pharmaceuticals for extended shelf life, food for travel, and scientific applications such as manuscript and painting restoration. Cryonics refers to the concept of freezing humans for revival at a later point, a concept that has not yet been realized.
In humans and animals, the most common side effect of exposure to the cold is dry skin. Long-term exposure can cause frosting, which painfully turns the top layer of skin turn white. Frostbite can occur after longer exposure or contact with metal objects. Essentially, frostbite blocks blood flow and results in numbness or cell damage to one's extremities. Hypothermia occurs after excessive heat is lost from the body and the inner core temperature drops below 95°F (35°C). Hypothermia can be fatal and will cause a person to shiver and be confused.
Most animals that live in cold environments have fur to protect against the cold. Not many plants can withstand extremely cold or prolonged low temperatures.
Freezer burn can occur to food stored below freezing for long periods of time. To prevent freezer burn, people should remove excess air from storage containers.
See also Food and Drug Administration ; Food safety .
Lebrun, P., and the European Organization for Nuclear Research. An Introduction to Cryogenics. Geneva, Switzerland: CERN, 2007.
U.S. Department of Health and Human Services. Extreme Cold: A Prevention Guide to Promote Your Personal Health and Safety. Atlanta, GA: Center for Disease Control, 2012.
Cavicchioli, R. “Low-temperature Extremophiles and Their Applications.” Current Opinion in Biotechnology 13, no. 3 (June 2002): 253–61.
U.S. Department of Agriculture. “Freezing and Food Safety.” http://www.fsis.usda.gov/Factsheets/Focus_On_Freezing/index.asp (accessed November 17, 2012).
Alyson C. Heimer, MA