Tropical and Extratropical Cyclones

Introduction

Tropical cyclones pose one of the greatest threats to human life and property even in their infancy. In this category, you’ll find everything from storm surges to flooding to high winds to tornadoes and lightning. Human life and property loss are greatly increased when these dangers are brought together. It is not uncommon for extratropical cyclones and hurricanes to be formed in areas with a wide range of temperatures, unlike tropical cyclones.

Categories of tropical cyclones

This is the tropical cyclone category system as used by the Bureau of Meteorology:

1. Category one (tropical cyclone)

Damage to the house was minimal. Some crops, trees, and caravans were damaged. Moorings can be dragged by craft. The strongest winds in a category one cyclone are GALES, with typical gusts of 90-125kph over open flat ground. These are Beaufort 8 and 9 winds (gales and strong gales).

1. Category two (tropical cyclone)

Damage to the house was not severe. Signs, trees, and caravans were severely damaged. Some crops have been severely harmed. There is a possibility of a power outage. Moorings can be damaged by small boats. The strongest winds of a category two storm are DESTRUCTIVE, with typical gusts of 125-164kph over open flat ground. These are Beaufort 10 and 11 winds (storm and violent storm).

1. Category three (severe tropical cyclone)

There is some structural damage to the roof. Some of the caravans were damaged in a fire. There’s a good chance of power outages. Over broad, flat land, 165-224kph gusts can be expected from a category three cyclone’s highest winds. The highest category on the Beaufort scale, Beaufort 12, is associated with these conditions (hurricane).

1. Category four (severe tropical cyclone)

Significant damage to the roof and the underlying structure. Several caravans were wrecked and blown away in the storm.. There is a danger of flying debris. Power outages have been reported in large parts of the country. The greatest winds of a category four hurricane are VERY DESTRUCTIVE, with typical gusts of 225-279 kph over open flat ground. The highest category on the Beaufort scale, Beaufort 12, is associated with these conditions (hurricane).

1. Category five (severe tropical cyclone)

Extremely dangerous, causing extensive damage. VERY DESTRUCTIVE winds characterise a category five cyclone, with maximum sustained winds of more than 280 kph over open, flat terrain. The highest category on the Beaufort scale, Beaufort 12, is associated with these conditions (hurricane).

Tropical Cyclones formation

Tropical cyclones are most likely to originate in warm ocean water near the equator. The ocean’s surface heat and moisture create cyclic air pressure. The air’s pressure is reduced as it rises above the water’s surface. In the low-pressure area, heat rises because of the movement of air from higher pressure zones.

As the rising moist air cools, water vapour condenses in the atmosphere. Weather patterns affect ocean surface heat and water evaporation.

As the wind system’s rotation speed increases, an eye forms at the system’s centre. The cyclone’s centre is peaceful and clear because of the lack of air pressure. The temperature difference between a hot and a sinking environment causes the air to rise and become buoyant.

Tropical cyclone

Tropical storm systems are defined by strong winds, a low-pressure centre, and an organised spiral of thunderstorms that generate heavy rain and/or strong squalls. A tropical cyclone can be referred to by a variety of names, depending on where it forms and how strong it is, including hurricane, typhoon, tropical storm, or cyclonic storm. Tropical cyclones in the Indian Ocean are commonly referred to as “tropical cyclones,” but in the northwestern Pacific Ocean, where they are more common, they are also known as “severe cyclonic storms.”. Even though they are both tropical cyclones, hurricanes and typhoons have their own unique characteristics that set them apart. They are called “tropical” because they are derived from tropical waters. In the Northern Hemisphere, “cyclones” are storms that revolve around a central clear eye and blow clockwise in the Southern Hemisphere. The reversal of circulation is due to the Coriolis effect. 

Tropical cyclones frequently form over large areas of moderately warm water. Their power comes from ocean evaporation, which cools as moist air rises from the depths to the surface and reaches a saturation point. There are three distinct types of tropical cyclones: typhoons, hurricanes, and cyclones that form over tropical oceans. Thunderstorms with wind speeds of more than 119 kilometres per hour (kph) are the norm in tropical storms (74 miles per hour). 

Cyclones pose a serious threat to coastal areas in tropical and subtropical regions around the world because of their high winds and water. On both sides of the equator, cyclones are common in the late summer (July–September in the Northern Hemisphere and January–March in the Southern Hemisphere). When it comes to tropical cyclones, they are known by a variety of different names around the world. Typhoons and hurricanes are tropical storms that occur in the eastern North Pacific and the northern Atlantic. Storms in the western South Pacific and Indian Oceans are called severe tropical cyclones, tropical cyclones, or cyclones for short. There is a common denominator among all of these terms.

Conditions for the formation of Tropical Cyclone

Tropical cyclone storms can form and intensify under the following conditions:

• Large sea surface with a temperature higher than 27° C
• Presence of the Coriolis force
• Differences in vertical wind speed are negligible.
• Existing low-pressure areas and cyclonic circulations
• Distinction above the surface of the ocean

Extra-tropical Cyclone

Extratropical cyclones (also known as mid-latitude or wave cyclones) are low-pressure systems that are responsible for much of Earth’s weather, in addition to high-pressure anticyclones. Extratropical cyclones are responsible for a wide variety of weather conditions. Large-scale (synoptic) low-pressure weather systems are affecting Earth’s mid latitudes right now. There are broad temperature and dew point changes near the centre of extratropical cyclones. It is thought that extratropical cyclones are formed by waves that form on a frontal surface that separates a warm and cold air mass. A cyclonic circulation is initiated as the wave’s amplitude increases, the disturbance’s core pressure decreases. When cold air from the north or south of a cyclone sweeps under warm tropical air, this happens. It can happen in either the Northern or Southern Hemispheres. The term for what you’re doing is occlusion, and you’re doing it.

Common weather patterns are linked to extratropical cyclones. The front side of the wave closest to the station is referred to as the “warm front,” and forecasters expect precipitation to begin shortly after stations ahead of this “warm front.” The rain will continue until the centre of the cyclone passes over the station. If a weather station is located far enough south of the cyclone’s centre, it will only be covered by the cold front as it passes over the area, which is the backside of the wave. At any given time, extratropical cyclones can be found in the high and middle latitudes. Despite the fact that these storms form and move in a predictable manner, there are always exceptions. Tropical cyclones are like this.

Condition for Extra Tropical Cyclone

Tropical storms are more likely to form and intensify if the following conditions are in place: Large areas of water having a surface temperature greater than or equal to 27 degrees Celsius. Coriolis force is present. The vertical wind speed can vary by a little amount. Warm air moves northwards and cold air moves southwards as the pressure drops along the front. This causes an anticlockwise cyclonic circulation. A well-developed additional tropical cyclone is formed as a result of the cyclonic circulation.

Conclusion

Conclusion

This chapter deals with cyclones which are an important part of geography and needs to be assessed well. Tropical cyclones pose one of the greatest threats to human life and property even in their infancy. In this category, you’ll find everything from storm surges to flooding to high winds to tornadoes and lightning. Human life and property loss are greatly increased when these dangers come together. It is not uncommon for extratropical cyclones and hurricanes to be formed in areas with a wide range of temperatures, unlike tropical cyclones. Keep updated with the material to do well in exams.