L.4. Formation of tropical cyclones

Question 1

1. Definition of a Tropical Cyclone

Answer 1

1. An area of low pressure with winds moving in a spiral around a calm central point called the eye of the storm – winds are powerful and rainfall is heavy

Question 2

HURRICANES/CYCLONES/TYPOONS

WHERE ARE THESE DIFFERENT NAMES USED?

Answer 2

Atlantic and eastern Pacific = hurricanes
(near the USA/Caribbean area )
Western Pacific = typhoons.​
(More near japan and east Asia)
Bay of Bengal and Indian ocean = cyclones (south/south east Asia, Australia) ​

Question 3

Coriolis effect? (simple)

Answer 3

a strong force created by the Earth’s rotation. It can cause storms; tropical cyclones

Question 4

Troposphere?

Answer 4

The lowest atmospheric layer. On average, it extends from the ground to about 10 kilometres (6 miles) high, ranging from about 6 kilometers (4 miles) at the poles to more than 16 kilometers (10 miles) at the Equator.

Question 5

Dissipate?

And why?

Answer 5

to (cause to) gradually disappear

They lose their source of energy

1. From moving away from the correct ocean temperature when they move to land
2. If they encounter cold water

Question 6

Intensity?

Answer 6

the quality or state of being intense especially: extreme degree of strength, force, energy, or feeling

Question 7

Storm-Surge?

Answer 7

a rapid rise in the level of the sea caused by low pressure and strong winds

Question 8

Saffir-Simpson scale?

Answer 8

a scale that classifies hurricanes into five different categories according to their wind strength
1-5

Question 9

Trade winds?

Answer 9

easterly winds that blow from high to low pressure, towards the Equator.

Question 10

Where do tropical cyclones normally form?

EQ-PEA

Answer 10

-Areas of low pressure so not all across the globe and not at the equator
-Around the line of Capricorn and line of Cancer
(where the Coriolis effect is stronger)
-They happen over oceans rather than land masses.

Question 11

What are areas where tropical cyclones normally formed called?

Answer 11

Source Areas

Question 12

Formation of cyclones: (In depth)

Answer 12

1. Ocean temp. needs to be at least 26.5 degrees Celsius.
   They also need to be between 5° and 20° north or south of the Equator.​
2. Warm and wet air rises, it condenses to form towering clouds, heavy rainfall. It also creates a low pressure zone near the surface of the water.​
   3.Rising warm air causes the pressure to decrease. The low pressure ‘sucks in’ air from the warm surroundings, which then also rises. A continuous upflow of warm and wet air continues to create clouds and rain.​
3. Air that surrounds the low pressure zone at the centre flows in a spiral at very high speeds - anti-clockwise in the northern hemisphere - at speeds of around 120 km/h (75 mph).​
4. The centre of the storm - the eye - is calm. The eye wall consists of the strongest winds.​
5. As the storm moves over the ocean, it picks up more warm moist air. The speed of its winds increase as more air is sucked in. ​
6. As hurricanes move inshore, their power gradually reduces because their energy comes from sucking up moist sea air. They dissipate as they hit land.

Question 13

Formation of cyclones - key ideas/words

Answer 13

key points:

• Ocean temp. = 26.5 °C
• 5° and 20° north or south of the Equator.​
• Warm, wet air rises—> condenses—-> cumulonimbus clouds form= heavy rainfall
• low pressure zone
• Low air pressure sucks in air(high to low pressure). The eye is calm but the eye wall has very strong winds.
• More moist air from the ocean means more energy for the storm resulting in stronger winds.
• Storm loses energy when is gets closer to land, they dissipate. Because it loses its supply of energy, its supply of moist air.

Question 14

Formation of cyclones-main and simple steps

Answer 14

Rising warm air evaporates and starts to spin B

· The warm ocean heats the air above an ocean on 26.5 degrees A

· Intense low-pressure sucks in air, causing very strong winds D

· The air then cools and condenses to form a towering cumulonimbus cloud C

Question 15

Coriolis effect: in detail

Answer 15

The Coriolis force is caused by the rotation of the Earth.
Earth spins on its axis from west to east, the earth is wider in the middle at the equator, which means the equator is spinning faster around the axis than the poles.​
It acts like a force to deflect a moving object on the Earth’s surface to the right in the northern hemisphere and to the left in the southern hemisphere​.
In the northern hemisphere storms spin anti-clockwise, but in the southern hemisphere they spin clockwise. ​

Question 16

What causes cyclones to spin?

EQ

Answer 16

The Coriolis effect is a force to do with earths spinning. Warm air rising creates areas low pressure. Then surrounding air rushes in trying to replace it, but it can’t simply rush in towards the middle, because of the Coriolis effect. It causes the air to rush in at a slight angle a bit off the centre, creating a vortex of spinning air.

Question 17

Explain two causes of Tropical Cyclones?

EQ: (4 Marks)

Answer 17

One cause of tropical cyclones forming would be warm air rising. (1) The oceans where cyclones form above have to have the temperature of at least 26.5 degrees Celsius. The heat from the sea causes the rapidly rising air and creates an area of low-pressure. Then surrounding air rushes in to replace this, causing strong winds

Another cause of tropical cyclones would be the Coriolis effect (1). The Coriolis effect is a force to do with earths spinning. Warm air rising creates areas low pressure. Then surrounding air rushes in trying to replace it, but it can’t simply rush in towards the middle, because of the Coriolis effect. It causes the air to rush in at a slight angle a bit off the centre, creating a vortex of spinning air.

Question 18

All source areas share some characteristics:​

Answer 18

Large, still, warm ocean area whose surface temperature exceed 26.5°C over long periods. This helps a body of warm air to develop. ​

Strong winds high in the troposphere, 10-12km above the earth. These are needed to draw warm air rapidly from the ocean surface. ​

A strong force created by the Earth’s rotation, called Coriolis force. They don’t form near the Equator where the Coriolis force is minimal, but instead where the rotation is stronger, between 5° and 30° latitude.