ATMOSPHERIC DISTURBANCES:
Temporary weather phenomena that occur due to changes in atmospheric conditions
like pressure, temperature, and moisture.
Types of Disturbances
1. CYCLONE :
A large system of winds rotating around a low-pressure center.
Winds move inward and counterclockwise in the Northern Hemisphere, and inward
and clockwise in the Southern Hemisphere.
2. Types of Cyclones
Tropical Cyclones:
Found in tropical regions (near the equator) 8DEGREE- 20 DEGREE N/S
LALITUDE.
Common in Bay of Bengal and Arabian sea
Strong winds, heavy rainfall, and thunderstorms.
Examples: Hurricanes (USA), Typhoons (Asia/ South China sea), Cyclones (India)
Willy-Willies (Australia).
Origin of Tropical Cyclones
1. Warm Ocean Water:
o Tropical cyclones form over oceans with surface temperatures above 26°C.
o Warm water heats the air above, causing it to rise.
2. Low-Pressure Area:
o Rising warm air creates a low-pressure zone at the surface.
o Cooler, moist air rushes in to replace the rising air.
3. Moisture and Condensation:
o Rising moist air cools and condenses into clouds.
o This process releases latent heat, which fuels the cyclone.
4. Coriolis Effect:
o Due to Earth’s rotation, the moving air is deflected, causing a spiral motion.
o Coriolis force is strongest near the equator, aiding cyclone formation.
5. Development of a Vortex:
o Air starts to rotate around the low-pressure center, forming a vortex.
o A fully developed cyclone has an eye (calm center) and eye wall (violent winds and
rain).
6. Favorable Conditions:
o Light upper-level winds to prevent disruption of the cyclone’s structure.
o Pre-existing weather disturbances like low-pressure troughs or tropical waves.
,Tornadoes: Detailed Facts and Concepts
1. What is a Tornado?
A tornado is a violently rotating column of air that extends from a thunderstorm to
the ground.
They are short-lived but extremely destructive.
Also known as twister for its twisting nature of cloud at its top
Most frequent on the central plains of missisipi basin in USA
2. Key Features
Shape: Funnel or rope-like.
Size: Varies, with diameters ranging from a few meters to more than 1 km.
Speed: Wind speeds can exceed 300 km/h in the most severe tornadoes.
Duration: Lasts from a few seconds to over an hour (average is about 10-15 minutes).
Path: Moves along the ground at speeds of 20–50 km/h.
3. Formation of Tornadoes
1. Severe Thunderstorms:
o Tornadoes form within powerful thunderstorms called supercells.
o Supercells have rotating updrafts known as mesocyclones.
2. Warm and Cold Air Interaction:
o Warm, moist air from the ground rises and meets cold, dry air above.
o The collision creates instability and rotation in the atmosphere.
3. Wind Shear:
o Changes in wind speed and direction with height cause horizontal spinning air.
o Rising air tilts the horizontal spin into a vertical vortex.
4. Formation of Funnel Cloud:
o As the vortex strengthens, it becomes visible as a funnel-shaped cloud.
o If the funnel touches the ground, it becomes a tornado.
Difference Between Tornadoes and Cyclones
Feature Tornado Cyclone
Size Small (100 m to 1 km wide). Large (100–1,000 km wide).
Duration Few seconds to an hour. Several hours to days.
Wind Speed Up to 300+ km/h. Up to 250 km/h.
Location Land (mostly). Oceans (moves toward land).
, What is a Waterspout?
A waterspout is a rotating column of air and water mist that forms over a water
surface.
It looks like a tornado but occurs over water.
. Formation of Waterspouts
1. Warm Water Surface:
o Warm water heats the air above it, causing the air to rise.
2. Low-Pressure Area:
o Rising warm air creates a low-pressure zone.
3. Rotation:
o Winds spin the rising air into a vortex.
4. Water Mist:
o Water is drawn upward by the vortex, creating a visible column.
Features of Waterspouts
Diameter: Typically 50–100 meters.
Height: Can reach up to 1,000 meters.
Speed: Winds can range from 50–100 km/h.
Lifespan: Lasts about 5–20 minutes.
(2)Temperate cyclone:
A temperate cyclone is a large-scale low-pressure system that forms in the mid-latitudes
(between 30° and 60° north and south of the equator).
These cyclones are associated with frontal systems, where warm and cold air masses meet.
2. Characteristics of Temperate Cyclones
Large size: Diameter ranges from 1,000 to 2,000 km.
Gentle winds: Winds are weaker compared to tropical cyclones.
Rain: Continuous, steady rain or showers associated with the cyclone.
Slow movement: Typically moves from west to east in the mid-latitudes.
Well-defined fronts: Warm and cold fronts are clearly visible.
3. Stages of Formation
1. Initial Stage:
o A low-pressure area forms along a frontal boundary between warm and cold air
masses.
o The warm air rises over the denser, cooler air (warm air is lighter).
2. Development Stage:
o The interaction of warm and cold air causes frontal lifting.
o The low-pressure system strengthens, creating a rotating motion.
Temporary weather phenomena that occur due to changes in atmospheric conditions
like pressure, temperature, and moisture.
Types of Disturbances
1. CYCLONE :
A large system of winds rotating around a low-pressure center.
Winds move inward and counterclockwise in the Northern Hemisphere, and inward
and clockwise in the Southern Hemisphere.
2. Types of Cyclones
Tropical Cyclones:
Found in tropical regions (near the equator) 8DEGREE- 20 DEGREE N/S
LALITUDE.
Common in Bay of Bengal and Arabian sea
Strong winds, heavy rainfall, and thunderstorms.
Examples: Hurricanes (USA), Typhoons (Asia/ South China sea), Cyclones (India)
Willy-Willies (Australia).
Origin of Tropical Cyclones
1. Warm Ocean Water:
o Tropical cyclones form over oceans with surface temperatures above 26°C.
o Warm water heats the air above, causing it to rise.
2. Low-Pressure Area:
o Rising warm air creates a low-pressure zone at the surface.
o Cooler, moist air rushes in to replace the rising air.
3. Moisture and Condensation:
o Rising moist air cools and condenses into clouds.
o This process releases latent heat, which fuels the cyclone.
4. Coriolis Effect:
o Due to Earth’s rotation, the moving air is deflected, causing a spiral motion.
o Coriolis force is strongest near the equator, aiding cyclone formation.
5. Development of a Vortex:
o Air starts to rotate around the low-pressure center, forming a vortex.
o A fully developed cyclone has an eye (calm center) and eye wall (violent winds and
rain).
6. Favorable Conditions:
o Light upper-level winds to prevent disruption of the cyclone’s structure.
o Pre-existing weather disturbances like low-pressure troughs or tropical waves.
,Tornadoes: Detailed Facts and Concepts
1. What is a Tornado?
A tornado is a violently rotating column of air that extends from a thunderstorm to
the ground.
They are short-lived but extremely destructive.
Also known as twister for its twisting nature of cloud at its top
Most frequent on the central plains of missisipi basin in USA
2. Key Features
Shape: Funnel or rope-like.
Size: Varies, with diameters ranging from a few meters to more than 1 km.
Speed: Wind speeds can exceed 300 km/h in the most severe tornadoes.
Duration: Lasts from a few seconds to over an hour (average is about 10-15 minutes).
Path: Moves along the ground at speeds of 20–50 km/h.
3. Formation of Tornadoes
1. Severe Thunderstorms:
o Tornadoes form within powerful thunderstorms called supercells.
o Supercells have rotating updrafts known as mesocyclones.
2. Warm and Cold Air Interaction:
o Warm, moist air from the ground rises and meets cold, dry air above.
o The collision creates instability and rotation in the atmosphere.
3. Wind Shear:
o Changes in wind speed and direction with height cause horizontal spinning air.
o Rising air tilts the horizontal spin into a vertical vortex.
4. Formation of Funnel Cloud:
o As the vortex strengthens, it becomes visible as a funnel-shaped cloud.
o If the funnel touches the ground, it becomes a tornado.
Difference Between Tornadoes and Cyclones
Feature Tornado Cyclone
Size Small (100 m to 1 km wide). Large (100–1,000 km wide).
Duration Few seconds to an hour. Several hours to days.
Wind Speed Up to 300+ km/h. Up to 250 km/h.
Location Land (mostly). Oceans (moves toward land).
, What is a Waterspout?
A waterspout is a rotating column of air and water mist that forms over a water
surface.
It looks like a tornado but occurs over water.
. Formation of Waterspouts
1. Warm Water Surface:
o Warm water heats the air above it, causing the air to rise.
2. Low-Pressure Area:
o Rising warm air creates a low-pressure zone.
3. Rotation:
o Winds spin the rising air into a vortex.
4. Water Mist:
o Water is drawn upward by the vortex, creating a visible column.
Features of Waterspouts
Diameter: Typically 50–100 meters.
Height: Can reach up to 1,000 meters.
Speed: Winds can range from 50–100 km/h.
Lifespan: Lasts about 5–20 minutes.
(2)Temperate cyclone:
A temperate cyclone is a large-scale low-pressure system that forms in the mid-latitudes
(between 30° and 60° north and south of the equator).
These cyclones are associated with frontal systems, where warm and cold air masses meet.
2. Characteristics of Temperate Cyclones
Large size: Diameter ranges from 1,000 to 2,000 km.
Gentle winds: Winds are weaker compared to tropical cyclones.
Rain: Continuous, steady rain or showers associated with the cyclone.
Slow movement: Typically moves from west to east in the mid-latitudes.
Well-defined fronts: Warm and cold fronts are clearly visible.
3. Stages of Formation
1. Initial Stage:
o A low-pressure area forms along a frontal boundary between warm and cold air
masses.
o The warm air rises over the denser, cooler air (warm air is lighter).
2. Development Stage:
o The interaction of warm and cold air causes frontal lifting.
o The low-pressure system strengthens, creating a rotating motion.
