Cold wave
A cold wave is a significant weather event characterized by a rapid drop in air temperatures over a 24-hour period, which can occur at any time of the year and in various locations worldwide. Meteorologists define cold waves by specific guidelines that consider the severity of temperature change and local climate norms. Typically, these waves originate from colder regions, such as northern Canada or Siberia, and are associated with high-pressure systems that stabilize the colder air. The interaction between different air masses and the jet stream contributes to the formation of cold waves, which can have widespread impacts.
Cold waves can lead to serious health risks, including frostbite and hypothermia for exposed individuals and animals, while also threatening agricultural crops and infrastructure. Historically, cold waves have resulted in severe conditions, as seen in events like the 2017 cold wave in northern India and the 2021 Texas freeze. Despite being less common than in the past, cold waves still pose significant challenges, affecting millions of people and disrupting normal life. Understanding cold waves is essential for preparedness, particularly in regions that may not be accustomed to severe cold conditions.
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Cold wave
A cold wave is a weather event that occurs when air temperatures drop rapidly within the span of twenty-four hours. Meteorologists, scientists who study the weather, use specific guidelines to define cold waves based on how quickly and how low the temperature drops. Cold waves can occur at any time of the year and in almost any place in the world. Meteorological guidelines used to define a cold wave vary depending on where and when it is occurring.
Background
The global pattern of winds is a significant driving force of Earth’s weather. These winds are formed by the uneven way the sun warms the planet. The tilt of the Earth in relation to the sun causes some parts of the Earth to heat more than others. This raises the air temperature in these areas and causes the air to move at different speeds. Hot air near the equator, the imaginary band around the horizontal middle of the planet, rises high into Earth’s atmosphere. This air spreads north and south until it reaches a distance of about 2,000 miles (3,220 kilometers) from the equator. It then falls back towards the Earth’s surface, generating winds known as convection currents.
Earth has six convection currents that push large air masses in front of them. These masses are thousands of feet thick and can be hot and humid or cold and dry, depending on what part of Earth they form over. At times, different air masses meet. Meteorologists call the place where two air masses come together a front. A cold front forms when colder air replaces a warmer air mass. A warm front occurs when warmer air catches up to and overrides colder air.
Air masses and fronts do not travel in straight lines. They are affected by strong winds high in the atmosphere known as jet streams. The shape of Earth beneath them can also cause them to cause directions. The interaction of air masses, fronts, the jet stream, Earth’s geography, and several other factors combine to create a variety of weather phenomena, including hurricanes, blizzards, and cold waves.
Overview
A cold wave is a large area of very cold and dense air that moves from the colder regions of the planet into warmer regions. In the Northern Hemisphere, these waves generally come from northern Canada or northern areas of Asia, such as Siberia. The term “wave” refers to the form of the jet stream in the upper atmosphere where it takes on an up-and-down pattern, much like an ocean wave.
High pressure systems help establish a cold wave. A high pressure system is an area where the atmospheric pressure on Earth’s surface is higher than the pressure of the surrounding areas. Atmospheric pressure is the downward force the air applies to the surface beneath it. It is also known as barometric pressure, after the device used to measure this pressure. A high pressure system that forms during cold weather is at the center of a cold wave.
When a high pressure system forms in cold weather and is accompanied by an upper level convergence, a cold wave often results. An upper level convergence happens when a strong wind moves into the area of a weak wind. This increases the strength of the high pressure area near the surface. These areas are directed towards the equator from the northern regions of the planet by upper atmosphere winds known as steering winds. The natural tendency of heavier cold air to move towards lighter, warmer air also helps move high pressure areas.
When these factors work to cause the temperature to drop severely over a twenty-four-hour period, meteorologists define the resulting change as a cold wave. This weather phenomenon covers a larger area than a blizzard or storm. The exact point at which a cold wave is declared depends on where on the planet it occurs and the time of year during which it happens. For example, a significant twenty-four-hour temperature drop to 20 degrees Fahrenheit (-7 Celsius) in the northern United States during winter months would be considered a cold wave. However, a cold wave might be declared in the southern states at a higher low temperature because the normal temperature there is warmer.
Cold waves can cause many problems. People and animal exposed to the cold temperatures for too long can suffer frostbite or other dangerous health issues such as hypothermia. Animals affected by a cold wave also need to consume more calories to generate sufficient body heat. Lack of sufficient food can result in starvation.
A cold wave can also devastate agricultural crops and other vegetation. In some cases, these waves can trigger storms that bring snow and ice. Prolonged bitterly cold temperatures can cause problems for infrastructure, such as damage to water pipes, vehicles, and other mechanical equipment. Planes are particularly vulnerable to damage from cold waves. A cold wave makes it more likely that ice accumulations will form on the wings and other surfaces of the plane. The metal surfaces of the plane can also be stressed by very cold temperatures, increasing the risk that parts of the plane could fail. The diesel fuel used in airplanes turns to a gel in extremely cold temperatures, which can affect the ability of airport personnel to refuel planes.
Scientists say that cold waves are not as common as they used to be, but they still occur fairly often. The United States experienced a severe cold wave in January and February 2019, and some areas were affected by extreme cold at the beginning of 2018 as well. In 2017, areas of northern India were affected by a strong cold wave in January that dropped temperatures into the single digits Fahrenheit and as low as -12 Celsius. The 2017 Indian cold wave was especially devastating because the people and buildings were not equipped with heat and other resources that are normal for colder climates. During the 2021 Texas freeze, the temperature reached zero in some parts of the state. It was the first billion-dollar disaster of the year. A cold wave in 2022 affected US states from Colorado to the Eastern Seaboard and even reached Florida. The cold wave affected thirty-six states and 110 million people.
Bibliography
“Cold Wave.” Skybrary, 3 Apr. 2019, www.skybrary.aero/index.php/Cold‗Wave. Accessed 7 Jan. 2020.
“Cold Wave.” University of Winnipeg, www.uwinnipeg.ca/emergency-guidelines/weather/cold-wave.html. Accessed 7 Jan. 2020.
“Divergence/Convergence/Confluence.” National Weather Service, www.weather.gov/source/zhu/ZHU‗Training‗Page/Miscellaneous/Divergence/divergence.html. Accessed 7 Jan. 2020.
"The Great Texas Freeze: February 11-20, 2021." National Centers for Environmental Information, 24 Feb. 2023, www.ncei.noaa.gov/news/great-texas-freeze-february-2021. Accessed 17 Nov. 2024.
“India Cold Wave: Delhi Reels from Coldest Day in More Than a Century.” BBC News,31 Dec. 2019, www.bbc.com/news/world-asia-india-50953950. Accessed 7 Jan. 2020.
Samenow, Jason. “In A Fast-Warming World, Scientists Say Recent Cold Wave Was Exceptionally Weird.” Washington Post,11 Jan. 2018, www.washingtonpost.com/news/capital-weather-gang/wp/2018/01/11/in-a-fast-warming-world-scientists-say-recent-cold-wave-was-exceptionally-weird/. Accessed 7 Jan. 2020.
“Weather Systems and Patterns.” National Oceanic and Atmospheric Association, 14 Feb. 2011, www.noaa.gov/education/resource-collections/weather-atmosphere-education-resources/weather-systems-patterns. Accessed 7 Jan. 2020.
“Where Do US Cold Waves Come From?” AccuWeather, 13 Feb. 2007, www.accuweather.com/en/weather-blogs/andrews/where-do-us-col/325130. Accessed 7 Jan. 2020.
Yu, Jin-Yi. “Cold Waves.” University of California, Irvine,www.ess.uci.edu/~yu/class/ess124/Lecture.14.coldwave.all.pdf. Accessed 7 Jan. 2020.