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Temperate Cyclones
A temperate cyclone is a specific type of storm that forms in the mid-latitudes. Although they differ in a number of ways, these storms are similar to tropical cyclones in several aspects. Temperate cyclone formation often takes place between October and April. They typically come from the Northern Hemisphere’s Gulf of Alaska or the waters off the coast of Japan. They frequently come from Argentina or the Tasman Sea in the Southern Hemisphere. The typical duration of a temperate cyclone is one week. While others can last up to two weeks, certain temperate cyclones can.
Low-pressure regions called temperate cyclones develop in the middle latitudes. Where the Jet Stream is greatest, between the 30th and 60th parallels, is where these cyclones often develop. Temperate cyclones can happen at any time of year, although the fall and winter are when they happen most frequently.
Temperate Cyclones are also referred to as Extra-tropical cyclones; the term “Extra-tropical” denotes the fact that this type of cyclone typically develops at latitudes between 30° and 60° outside of the tropics. The topic of temperate cyclones is discussed here. This is a significant section of the NCERT notes that is pertinent for IAS hopefuls. The UPSC aspirants would find this article quite helpful.
Read More: Anticyclones
Cyclones
Cyclones are local low-pressure systems with converging air from surrounding areas. The Coriolis Force deflects the cyclone and provides a whirling motion. Cyclones spiral motion is in a counter-clockwise direction in the Northern hemisphere and in a clockwise direction in the Southern hemisphere. The isobars (imaginary lines joining similar pressure gradients) are closely looped- near-circular or elliptical. Cyclones are broadly divided into two types:
- Temperate Cyclones
- Tropical Cyclones
Temperate Cyclones Phenomena
The temperate cyclone is one of the most important atmospheric phenomena affecting weather in the middle latitudes. They are also known as extra-tropical cyclones (beyond tropics) or mid-latitude cyclones or frontal cyclones. They are low-pressure systems with associated cold fronts, warm fronts and occluded fronts. They are an integral part of the global air circulation involved in heat transfer thus maintaining the Heat Budget of Earth.
Temperate Cyclones Formation
The formation of the temperate cyclone is explained by the Polar Front theory by Bjerkens and Bjerkens, which was propounded during World War 1.
Stage I Frontogenesis
Two air masses converge along the sub-polar low-pressure belt in the northern hemisphere. The cold air mass moves southward and the warm air mass moves northward and forms a boundary where the winds blow parallel but in opposite directions.
Stage II Cyclogenesis
The contrasting air masses start intruding into each other’s territory. The warm air mass intrudes into the area occupied by the cold air and the cold air mass intrudes into the warm air mass. This is how the wave formation begins and sets the stage for a full-fledged cyclonic circulation.
Stage III Mature Stage
After the circulation sets in, the waveforms. There is a greater intrusion and occupation of the air mass into each other’s territory. The warm air mass intrudes further, and the cold air mass moves towards the equator along the cold front boundary. This is the mature stage of cyclonic circulation.
Stage IV Occlusion Stage
The cold front having a greater speed of intrusion than the warm front intrudes into the warm sector. This results in the shrinkage of the warm sector and gradually the cold front overtakes the warm front. The two air masses eventually mix across the front. The occluded front is eliminated. Eventually, the cyclone dies out.
Temperate Cyclones Characteristics
- The storm systems known as Extra-Tropical Cyclones form away from the tropics in the mid-to-high latitudes.
- These low-pressure systems are accompanied by occluded, warm, and cold fronts.
- These storms develop alongside the polar front.
- The front remains motionless at first.
- Mid-latitude storms and baroclinic storms are other names for extra-tropical cyclones.
- Warm air blows from the south of the front and cold air from the north in the Northern Hemisphere.
- An anticlockwise cyclonic circulation begins when the pressure decreases along the front, causing the warm air to flow north and the cold air to move south.
- A well-constructed extratropical cyclone with a cold front and a warm front is produced by cyclonic circulation.
- Between the chilly air in the front and the warm air in the back are squeezed pockets of warm air.
- In advance of the warm front, a number of clouds form across the sky and start to rain as the warm air moves over the cold air.
- The warm air is forced upward as the cold front approaches from behind.
- Cumulus clouds consequently grow near the cold front.
- The warm front eventually loses ground to the cold front as it advances more quickly.
- The front is completely obscured, the warm air is completely lifted, and the cyclone evaporates.
- They can come from both land and water, and they can cover a bigger region.
Temperate Cyclones Map
The temperate cyclones extend over the Sierra Nevada, Colorado region, and Great Lakes region of North America. Mediterranean, Russia, and even India (Western disturbances).
Temperate Cyclone Movement
Generally speaking, temperate cyclones are less organised than tropical cyclones. Usually, they travel from west to east across continents. They revolve around a centre of low pressure in the Northern Hemisphere in an anticlockwise direction, while in the Southern Hemisphere, they revolve in a clockwise direction. Although they can develop at any time of the year, temperate cyclones most frequently do so between September and May.
Temperate Cyclone Associated Weather
A temperate cyclone’s anticlockwise air movement can produce widespread showers and thunderstorms. These storms frequently bring with them wind gusts, torrential rain, and occasionally hail. Tornadoes can also be caused by temperate cyclones.
Strong winds are typically a temperate cyclone’s most dangerous feature. These systems’ related winds have the potential to harm buildings, trees, and electricity lines. Large waves can also be produced by temperate cyclones at coastlines. These waves may result in flooding and deterioration of the beach.
Strong winds, lots of rain or snow, and thunderstorms are just a few of the meteorological characteristics that temperate cyclones can bring. Tornadoes can sometimes develop from temperate cyclones. Sandy, a temperate cyclone that hit the northeastern United States in 2012, was the most destructive in recent memory. Contrary to their name, temperate cyclones can form in both tropical and temperate areas.
Differences between Temperate Cyclone & Tropical Cyclone
| Tropical Cyclone | Temperate Cyclone |
| Tropical cyclones go westward from eastward. | These cyclones travel eastward from westward. |
| Comparatively speaking, a tropical storm affects a lesser region than a temperate cyclone. | A substantially wider area is affected by temperate cyclones. |
| In a tropical cyclone, the wind is blowing significantly faster and more destructively. | Air moves at a relatively slower speed. |
| Only in waters that are warmer than 26–27 degrees Celsius do tropical cyclones form, and they vanish once they land. | Both on land and in the ocean, temperate cyclones can develop. |
| One tropical cyclone lasts no longer than seven days. | A temperate cyclone can persist for between 15 and 20 days. |
Tropical Cyclone UPSC
When two opposing air masses, such as thin polar air masses and heavy tropical air masses, clash, temperate cyclones are created. Extra-tropical cyclones are another name for temperate cyclones. Extra-tropical describes cyclones that form in a latitude range of 30° to 60° and take place outside of the tropics. You will learn about Temperate Cyclones in this article, which will help you with your preparation for the UPSC Civil Service Exam in geography.
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