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Cyclones, anticyclones, and their types and characteristics are described as follows: 

Meaning of cyclone: Cyclone is commonly used to refer to the center of low air pressure, around which the air pressure increases gradually. Because of this, the winds flow from all around directions to the center. 

Their shape is usually elliptical, circular or W shaped.

1. Temperate cyclone: Such types of cyclones originate in the mid latitudes. At the center of the airturbulence in mid-latitudes, there is less pressure in center and more pressure is there on the periphery. They are often called low or deep or trough. These cyclones originate from the interaction of the air – masses of opposite nature. The area of these cyclones is found in both the hemispheres between 35° to 65° latitude. Clouds originate in the atmosphere from these cyclones. Under favorable conditions, these cause either rainfall or snowfall.

2. Tropical cyclone: This type of cyclone is found on both sides of the Equator between the Tropic of Cancer and Capricorn. They appear in many forms. They take a violent and rapid form and create destruction in the areas they hit. As in temperate cyclones, uniformity is not found in these cyclones.

Characteristics of Cyclones: 

1. Cyclones are the centers of low air pressure and in which the air pressure increases from the center towards the periphery. 

2. Winds move from the periphery to the center. 

3. Their shape is similar elliptical, circular, or ‘V’ oriented. 

4. They affect the weather.

Meaning of anti – cyclone: The anti – cyclone is a sequence of circular isobars in which the air pressure is high at the center and it decreases gradually toward the outside.

Types of Anti – cyclones: 

Anti – cyclones are divided mainly into the following categories:

1. Cold Anti – cyclone: These anti – cyclones form in polar regions primarily in arctic regions. These move forward in the east and south – east direction. They are smaller in size than warm anti – cyclones:

2. Warm Anti – cyclone: These anticyclones are produced in the belt of temperate high air pressure. In this belt, there is divergence of winds. Their size is huge. These are less active.

3. Blocking Anti – cyclone: This is a new type of anti – cyclone. These cyclones originate due to obstruction of wind circulation in the upper part of the troposphere. Among these, the air system and weather characteristics are similar to warm anti – cyclones. They are smaller and slower in speed.

Characteristics of anti – cyclones: 

1. There is high air pressure in the center of every anti – cyclone, which decreases towards the periphery. 

2. Winds blow in the clockwise direction in the northern hemisphere, and in the southern hemisphere, in the anti – clockwise direction.

3. Size is larger than cyclones. Their size is often spherical. 

4. The weather becomes clear, the sky becomes clean and the wind becomes hot due to the arrival of anti – cyclones. 

5. These occur more in sub – tropical high pressure areas.

(b) Lam – pert and Shaw

(b) Tropical cyclone

Correct Answer is: (c) S

Correct Answer is: (d) CT

(a) South – east Asia

In the parallel movement of two opposing air – masses, separation and absence of peripheral motion of the air is called stationary front.

When two opposite – natured air – masses (cold and hot) blow in, they try to retain their identity related to temperature and humidity. In this process, a sloping border develops in between, which is called front.

Types of front: 

The fronts are mainly divided into the following parts:

1. Warm Front: The front which originates by warm air advances over the cold air. 

2. Cold Front: The front which originates by cold air advancing over the warm air. 

3. Stationary Front: Front which originates due to the two opposing fronts being parallel. 

4. Occluded Front: Occluded front is formed when a cold air – mass overtakes a warm air – mass and goes beneath it.

The warm front is formed by the advancement of warm air over cold air.

On the basis of their region of origin, the air – masses are divided into tropical and polar air – masses. On the same basis, continental and oceanic air – masses are found.

The wide tropical cyclones surrounded by several isobars are called hurricanes in the United States. Their speed is usually 120 km/ph. They are very giant and stubborn. Their number is very low and they occur sometimes. These types of hurricanes often occur only in certain parts of the tropical lines. They cause torrential rains. Their direction is from east to west.

The following conditions are necessary for the origin of the front: 

1. Air – masses of different nature: When the opposite variants of air meet, they attempt to enter each other’s area, which creates a wave – type front.

2. The difference in humidity: Less or more humidity found due to atmospheric conditions is helpful in the formation of fronts. 

3. Atmospheric circulation: Horizontal and vertical movement of winds and their convergence and divergence are helpful in creating fronts.

Cyclone usually refers to the region of low air pressure, around which the air pressure increases, gradually, due to which the winds flow from all the directions towards the center.

When the air – mass is hot or cold below on its surface due to the exchange of heat between the surface and the base of the air – mass, it is called thermodynamic conversion.

The region where air – masses are produced are called the area of their origin.

When atmospheric conditions are stable on a wide surface plane, the air contains surface humidity and temperature related characteristics, which causes the formation of the air – masses.

The wide and dense part of the atmosphere is called the air – mass, whose physical properties, especially the temperature and humidity, are same nearly identical in horizontal shape.

The conversion that occurs in the air – mass, which is free from the heating and cooling provided by the surface, is called mechanical conversion.

(c) Ocean polar

Correct Answer is: (b) Burkineze

According to Triwartha, “Cyclones are relatively low air pressure areas, which are surrounded by centric and surrounding isobars.”

The anticyclones are categorized into mainly three types: the cold anticyclone, the warm anticyclone and the blocking anticyclone.

Tornado is the smallest but most terrible and destructive tropical cyclone in terms of its effect, which mainly occurs in the Mississippi Valley of the United States, and in Australia in a minor form.

Correct Answer is: (a) Warm front

Obstruction of wind circulation in the upper part of the troposphere causes Blocking Anticyclone.

Correct Answer is: (b) 4

In the Arctic territories, due to excessively high temperature caused by radiation and low insolation, high air pressure is formed during the winter, resulting in the origin of cold anticyclones.

Tropical cyclones originate in the oceans between 8° to 15° North latitudes.

The jet stream is divided into two parts: Sub – Tropical Jet Stream and the Latitudinal or Polar Front Jet Stream.

Correct Answer is: (a) Front

When the hot and light air is lifted by the cold and heavy air, the front so formed is called cold front.

The following six ideal generating regions of air – masses are found on the earth: 

1. Polar ocean area (the northern region of the Atlantic and Pacific Ocean) – In these areas, the air – masses are produced during the winter. 

2. Sub – Polar continental zone (glaciated part of Eurasia and North America and Arctic region) – In these areas, the air – masses arise during the winter period. 

3. Monsoon Area (South – East Asia) – This includes India, Bangladesh, Indonesia, Indo – China region. 

4. Tropical ocean area (anticyclone area – winter and summer). 

5. Tropical continental region (Mississippi Valley Area of North America, Asia and North Africa). 

6. Equatorial linear areas – Air – masses originate in these areas due to convectional conditions.

The cold anticyclones arising in the polar regions have been divided into the following categories on the basis of activation:

1. Temporary and transient anticyclone. 

2. Semi – permanent anticyclone.

1. Temporary and transient anticyclone: This type of anticyclone ends on their way by themselves. Only a few of these reach the tropics. 

2. Semi – permanent anticyclone: These are more active and the path of these types of anticyclones is also extended.

The conditions found in tropical cyclones are as follows: 

1. Low air pressure exists in their center and the shape of their isobars is circular. 

2. There is a large variation in their speed. At some places their speed is 32 km/h and at other places it is up to 200 km. per hour. 

3. There is considerable variation in their size. Normally, their diameter ranges from 80 to 300 km. 

4. These cyclones are permanent. They cause rainfall at one place for several days. 

5. These cyclones are more destructive. 

6. These cyclones move fast over the oceans, but they weaken after coming to the land.

Characteristics of Cyclones:

1. Cyclones are the centers of low air pressure in which the air pressure decreases towards the outside from the center. 

2. Winds move from the periphery to the center. 

3. The shape of cyclone shape is elliptical, circular, or ‘V’ shaped. 

4. Cyclone, affects the weather due to which, decline in air pressure, formation of halo around the Moon and the Sun, the occurrence of heavy rain, etc. take place. 

5. In the Northern Hemisphere, the wind blows in the anti – clockwise direction, and clockwise direction in the southern hemisphere.

The process of changes in the characteristics of air – masses after their origin due to their movement in other areas (other than origin area) air – masses is called conversion. 

The process of conversion in the air – masses has been clarified as follows:

When the air – masses pass through the other area after leaving the area of their origin, they are converted in various sequential steps.

This conversion is of two types: 

1. Thermodynamic conversion 

2. mechanical conversion.

1. Thermodynamic Conversion: When the air – mass gets heated up or cooled down from below the surface due to the exchange of heat between the surface and the land surface (Basal plane) of the air – masses, it is called Thermodynamic Conversion.

2. Mechanical Conversion: The conversion that occurs in the air – masses, which is free from the heating and cooling provided by the surface is called Mechanical Conversion. For example, the conversion of cyclones, anticyclones, and air due to the vertical movement of air.

Air – masses are classified on the following two basis:

1. The nature of the origin area. 

2. Conversion of the air – mass.

On the basis of the nature of their area of origin, there are two types of air – masses: the tropical and the polar air – mass. Since the origin area can be either oceans or continents, therefore they can be divided into two sub – classes: sea tropical, continental tropical, sea-polar and continental polar. Due to high humidity in the sea air – masses, they cause excessive rainfall. In contrast, continental air – masses are dry and therefore they cause less rainfall.

The various physical traits found in temperate cyclones are as follows:

1. Before the advent of these cyclones, long but thin stripes of white clouds appear in the sky. 

2. Before their arrival, the mercury falls continuously in the barometer. 

3. The presence of Halo around Sun and Moon is a sign of their coming. 

4. Before their arrival, the winds begin to change their direction. 

5. Due to the lack of air, if the drains emit a foul smell, than its (cyclone) coming gets confirmed.

Air – masses are the atmospheric conditions found in a wide area. 

They have the following characteristics:

1. Air – masses are extended to hundreds of kilometers. 

2. There are many layers in the air – masses. 

3. In each horizontal layer of air – masses, there are uniform properties. 

4. Once generated, the air – masses do not remain stable in the area of their origin. 

5. Air – masses affect the area which comes in their contact. 

6. While affecting the area, their own qualities also change. 

7. Due to their large size, the change in the air – masses takes place at a lesser speed.

Jet stream plays an important role in creating, inducing, and magnifying fierce weather events such as cyclones, anticyclones, monsoons, furious winds and storms.

The polar front jet stream originates in both hemispheres between 40° to 60° latitudes.

When a cyclone arrives, air pressure falls. A halo around the Moon and the Sun is formed, and, it affects the weather by causing heavy rainfall.

There are two types of conversions in air – masses: 

1. Thermodynamic conversion. 

2. mechanical conversion.

(c) Near 60° latitude

(b) Tropical ocean area

Cyclone commonly refers to the center of low air pressure, around which the air pressure gradually increases. Because of this the winds flow from all the directions towards the center. 

Their shape is usually elliptical, circular or ‘V’ oriented.

Origin of temperate cyclone: Temperate cyclones originate mainly on polar fronts. But their origin can be anywhere outside the tropical zone. Their origin and development is more in the winter season. In the northern hemisphere, these cyclones range from the western coastal parts of the North Pacific Ocean to the Aleutian inland area and from the western shore of the North Atlantic Ocean to the lowlands in Iceland, besides this China, Philippines, Siberia are other major areas. In the southern hemisphere, these cyclones form in both summer and winter in a similar manner. Most cyclones occur around 60° south latitudes here.

Types of temperate cyclones: 

These cyclones are divided into the following parts:

1. Thermal Cyclone: This type of cyclone develops from creation of a low pressure center on the continents due to excessive heat in the temperate regions. In these, the winds move from outside to the center. These are often permanent. These are often formed from low pressure centers over the ocean.

2. Dynamic Cyclone: The origin of the Cyclones is due to the support obtained from conjunction of fronts of cold polar and warm tropical oceanic air – masses. These cyclones affect wide areas.

3. Migrant Cyclone: These types of cyclones occur sometimes. These are the results of specific situations.

(a) anti – clockwise

Tropical cyclones originate from the equatorial region between the Tropic of Cancer and Capricorn.

(d) Temporary front

Following are the major theories of origin of cyclones: 

1. Local Warming Theory: According to this theory, the areas where the heat is high or the temperature is high, the air starts getting heated up fast. Hot air rises and cyclonic conditions arise due to the development of the center of low air pressure. 

2. Dynamic Theory: Vortex is produced in the lower layers of the atmosphere due to several reasons which cause the cyclone to be produced. 

3. Polar Front Theory: According to this theory, the emergence of the cyclones is based on the formation of front. The fronts created by the presence of different air – masses form the cyclone.