9.3: Hazards resulting from atmospheric disturbances

Question 1

what are the conditions needed for tropical cyclones to form

Answer 1

sea temp over 26.5 C
tropics (8-20 latitude)
coriolis force
low wind shear
low atmospheric/air pressure

Question 1

tropical storm definition

Answer 1

a very intense low air pressure system with high winds and rain. It rotates anti-clockwise in the N hemisphere

Question 2

define latent heat

Answer 2

The energy absorbed or released during a phase change of a substance like when water vapour condenses into liquid water, without changing its temperature. In tropical storms, this released energy warms the surrounding it, fueling the storm

Question 3

define rainbands

Answer 3

a cloud and precipitation structure associated with an area of rainfall which is significantly elongated

Question 4

eyewall

Answer 4

the eyewall consists of a ring of tall thunderstorms that produce heavy rains and usually the strongest winds

Question 5

eye

Answer 5

the calm center of the storm. the eye is usually 32-48 km across. it is an area of light wind speeds and no rain . it contains descending air

Question 6

storm surge

Answer 6

the abnormal rise in seawater level during a storm. Caused by low air pressure and winds pushing water onshore

Question 7

coriolis effect

Answer 7

the coriolis effect makes storms swirl clockwise in the southern hemisphere and counterclockwise in the northern hemisphere

Question 8

trade winds

Answer 8

permanent east-to-west prevailing winds that flow in the earths equatorial region

Question 9

convection

Answer 9

vertical transport of heat and moisture in the atmosphere, especially by updrafts and down drafts in an unstable atmosphere

Question 10

explain the key features of a tropical storm

Answer 10

tropical cyclones form over a sea with a temperature of 27 C. The warm water evaporates into the air making

Question 11

Why do tropical storms die out when they reach land?

Answer 11

A lack of moisture supply from the warm ocean surface leading to reduced convection

Increased friction as the disturbance moves over land disrupting the organised circulation of the storm and reducing wind speeds

The system no longer benefits from the thermal energy and latent heat that drove its development. The cooling effect over land reduces the storm intensity

Question 12

compare a category 2 storm to a category 4 storm

Answer 12

Category 2 storms have average wind speeds of 96-110 mphs whereas category 4 storms have average wind speeds of 130 - 156 mphs. Category 4 storms can also cause greater damage

Question 13

air pressure imbalances description

Answer 13

significant air pressure imbalances due to the extremely low central pressure within the storm, which affects weather patterns in surrounding areas

Question 14

how does air pressure imbalances occur

Answer 14

as the tropical disturbance rotates, a strong pressure gradient forms between the low pressure center and the higher pressure surrounding it. This imbalance can cause abrupt changes in weather patterns, including sudden drops in temperature and pressure

Question 15

why are air pressure imbalances hazardous?

Answer 15

rapid changes in air pressure can impact human health, particularly in individuals sensitive to pressure changes and may worsen pre-existing respiratory and circulatory conditions. additionally, these imbalances lead to changes in wind patterns and ocean currents that can affect weather far beyond the immediate storm zone.

Hurricane Katrina, at its peak intensity had an extremely low central air pressure of 902 millibars )mb). This intense pressure imbalance contributed to its strength as a category 5 hurricane before it weakened slightly as it made landfall.

Question 16

coastal flooding description

Answer 16

rise in sea levels and saturation of coastal land

Question 17

how does coastal flooding occur

Answer 17

caused by storm surge, heavy rainfall which overwhelms drainage systems and causes widespread flooding. strong winds and large waves also contribute to flooding. made worse if this coincides with high tide

Question 18

why is coastal flooding hazardous

Answer 18

loss of life, damage to property, coastal ecosystem such as wetlands, beaches and mangroves destroyed. long term displacement of people

Typhoon haiyan (2013) in the Philippines caused widespread coastal flooding due to a powerful storm surge which affected several cities and resulted in severe infrastructure damage

Question 19

high winds description

Answer 19

strong winds that cause damage to buildings trees and infrastructure

Question 20

what causes high winds?

Answer 20

where atmospheric pressure differences lead to fast moving air currents

Question 21

how can high winds be hazardous?

Answer 21

objects lifted can cause secondary damage as projectiles and impacting people animal and structure. Building collapse. Most vulnerable parts are roofs, windows and doors. Uprooting of trees and habitat destruction. Soil erosion as high winds can remove top soil

Typhoon Haiyan had sustained wind speeds of 195-235 mph

Question 22

intense rainfall description

Answer 22

rise in sea level and saturation of coastal land

Question 23

how can intense rainfall cause floods

Answer 23

this can rapidly increase river volume exceeds the bankfull capacity, causing the bank to burst and resulting in floods. In cities impermeable surfaces like concrete prevent the absorption of rainwater exacerbating the risk and severity of floods

Question 24

other than causing floods, how can intense rainfall be hazardous

Answer 24

damage to agricultural land and crops. significant economic impacts and the displacement of communities and disruption of everyday life.

Over the course of Hurricane Katrina, it dropped more than 8 inches of rain in many areas with some regions receiving more than 10 inches. In total the storm caused catastrophic flooding, particularly in New Orleans where levees were breached

Question 25

storm surge description

Answer 25

a large rise in sea levels caused by low pressure and high onshore winds, pushing water towards the coast

Question 26

explain why a tropical disturbance may not develop into a tropical storm (5)

Answer 26

A tropical disturbance requires with high windshear may not develop into a tropical storm. This is because it can rip the tropical storm apart. If there is a tropical disturbance in the …………………….

Question 27

Outline the possible reasons for the source and direction of movement of the hurricanes

Answer 27

Hurricanes originate over tropical oceans with sea surface temperatures above 26.5°C, where evaporation and condensation drive cyclonic activity. Hurricane Katrina formed near the Bahamas in 2005 and intensified over the warm waters of the Gulf of Mexico.

Hurricane movement is influenced by trade winds, which initially direct storms westward, and the Coriolis effect, which curves them northward and then northeastward as they move poleward. Katrina followed this pattern, moving westward toward Florida, then northward before making landfall in Louisiana. High-pressure systems, such as the subtropical ridge, also steer hurricanes. Katrina’s path was shaped by these forces, and it weakened after landfall due to friction and loss of moisture.

Question 28

What is a tornado

Answer 28

A tornado is a rapidly rotating column of air that extends from a thunderstorm to the ground, characterised by its funnel shape and destructive winds

Question 30

Insolation

Answer 30

Incoming solar radiation, The amount of solar energy received by a given areas over a specific time period

Question 31

Supercell

Answer 31

A highly organised and long-lived thunderstorm characterised by a rotating updraft called a mesocyclone, Supercells are capable of producing severe weather such as hail, strong winds and tornadoes

Question 32

Mesocyclone

Answer 32

A rotating column of air within a convective storm.

Question 33

Anemometer

Answer 33

A device used to measure wind speed and direction.

Question 34

Barometer

Answer 34

An instrument used to measure atmospheric pressure.

Question 35

Enhanced Fujita Scale

Answer 35

A scale used to classify the intensity of tornadoes based on the damage they cause. Each category is associated with estimated wind speeds and corresponding damage descriptions.

Question 36

Tornado alley

Answer 36

A region in the central United States that is prone to tornadoes. Includes parts of Texas, Oklahoma, Kansas, Nebraska and South Dakota.

Question 37

Waterspout

Answer 37

A tornado that occurs over a body of water

Question 38

What are the four key ingredients of tornado formation?

Answer 38

Moisture: provides energy source, Instability: ensures vigorous upward movement of air, Lift: triggers the initial upward motion needed for storm formation, Wind Shear: organizes and intensifies rotation, leading to the funnel cloud and potential tornado

Question 39

How is a tornado formed

Answer 39

Within the storm, a strong vertical wind shear causes a horizontally rotating cylinder of air. The updraft lifts the rotating supercell. The rotating cylinder of air narrows, becoming stretched and spins faster and faster forming a tornado

Question 40

Explain the formation of tornadoes (5)

Answer 40

Tornadoes form in stages, starting with a supercell thunderstorm. Warm, moist air rises and meets cold, dry air aloft, creating instability. Strong updrafts form, and wind shear causes horizontal air rotation.

The updraft tilts this rotation vertically, forming a mesocyclone—a key feature of tornado development. The mesocyclone strengthens the storm’s rotation and draws in warm, moist air, increasing instability.

As the mesocyclone intensifies, cooling air condenses into a funnel cloud, with latent heat release further fueling the storm. If the funnel cloud extends to the ground, it becomes a tornado, causing destructive winds.

The tornado dissipates when the updraft weakens, rotation slows, and the funnel cloud shrinks and disappears.