GCSE AQA Geography Section A: Weather Hazards

Hurricanes form on...

Hurricanes form on...

sea

Tornados form on...

land

What is the definition of weather?

The condition of the atmosphere over a short period of time

What is the definition of climate?

Average weather conditions over a long period of time

What is the definition of the global atmospheric circulation?

The natural movement of air around the Earth which helps to balance global temperatures

What are the factors which affect weather and climate?

• latitude

• curvature of the earth

• air pressure

• pressure cells

• wind

How does high pressure work + conditions in a high pressure environment?

the air is sinking

CONDITIONS

• clear skies because air is sinking, therefore, clouds cannot form

• little cloud

• fog

How does low pressure work + conditions in a low pressure environment?

hot air is rising

CONDITIONS

• rain

• clouds because air is rising, therefore, forming clouds

• wind

How does a Hadley cell work?

1. Warm air rises at the equator, producing a lot of precipitation.

2. At 30, cool dry air drops down, without precipitation. (LOW TO HIGH PRESSURE)

What environments form at the equator? + why

Rain forests -> high temperatures means evaporation happens at fast rates, therefore, frequent rainfall.

How does the Ferrell cell work?

1. warm air rises from 30,

2. it rises to 60 and then falls back to 30 (HIGH TO LOW PRESSURE)

How does the polar cell work?

1. air rises/falls from 60 to North and South

2. cools and returns to 60 (LOW TO HIGH PRESSURE)

What does latitude mean?

Angular distance of a place north or south of Earth's equator

What are the 5 main lines of latitude?

• Arctic Circle

• Tropics of Cancer

• Equator

• Tropics of Capricorn

• Antarctic Circle

What does latitude determine?

Seasons because of the Earth's tilt at 23.5°

What is the Coriolis Effect?

The effect of Earth's rotation on the direction of winds and currents.

What are surface winds?

They transfer heat and moisture from one place to another

What type of pressure is a tropical storm?

Low pressure -> wind and rain

What measures hurricanes?

Saffir-Simpson Scale - strength of tropical storm

What specific wind speed is needed to identify a hurricane?

74mph (category 1 tropical storm) > anything below is a storm

What temperature does the sea need to be to form a hurricane?

27°C + shallow oceans as they warm up quicker

What season are tropical storms most common?

Mid late summer

Where are hurricanes found?

Atlantic Ocean near Caribbean Sea, off the coast of Africa, Gulf of Mexico.

What do storm surges create?

Creates coastal flooding

What percentage of hurricane deaths are from the result of storm surges?

90%

Why do hurricanes not form on the equator?

Coriolis effect doesn't affect the Equator, therefore, lack of spin which is required for a hurricane

How do tropical storms form?

1. upward movement of air drawing water vapour from ocean surface (27+ degrees)

2. evaporated air rises and cools to form thunderstorm clouds

3. air condenses releasing heat -> more power

4. small spiralling thunderstorms join together to create a giant storm

5. storm develops at the edge of the eye, eye wall has the most intense conditions

6. storm gathers strength as it moves through the ocean

7. once it reaches land, energy supply weakens and friction weakens storm

How does climate change affect tropical storms?

• warmer air = more water vapour = more energy to intensify hurricanes

• melting ice = more water to absorb heat and sea ice reflects heat

• weather events becoming more intense + frequent

• weather records broken

What act methods are there in preparing for a storm?

BUILDING DEFENCES

• boarding up windows + doors

• securing anything which could be blown away

EVACUATION

What forecasting methods can help prepare for a storm?

SUPERCOMPUTERS

• data need to be sorted + predictions calculated by massive, high-tech supercomputers

TEAMWORK

• some countries cannot afford predictive tech, therefore, 'Joint Typhoon Centre' (pacific) or "National Hurricane Centre" (Atlantic) help prepare for storms

What preparation techniques are there to prepare for a storm?

BUILDING DESIGN

• raising electrics, building on stilts, building cyclone shelters and building away from rivers

BUILDING ADAPTATION

• boarding up windows and doors buying windproof tiles, water-resistant windows and strengthened building structures

what are the five air masses in the U.K? + where do they come from + their conditions?

Polar Maritime {cold + wet // Greenland + Arctic Sea}

Arctic Maritime {colder + wet // Arctic}

Polar Continental {coldest + dry // Central Europe}

Tropical Maritime {warm + wet // Atlantic Ocean}

Tropical Continental {warm + dry // North Africa}

Jet streams from the South are _____ air

warm

What pressure cells are the U.K between? + latitude

U.K. is at 55° latitude -> between Ferrell and Polar cells - a.k.a 'The Polar Front' so we're affected by low pressure: rain, cold weather + fog

What is a jet stream?

A jet stream are high level atmospheric winds that can influence the U.K. weather; they meander like a river.

Jet streams from the North are ______ air

cold

Numerical evidence of climate change

-20 warmest years measured in past 22 years

• 2015, 2016 and 2017 hottest years recorded

• humans emitted 1.5 trillion tonnes of CO2 to Earth's atmosphere

• wildfires struck California and Greece, heatwave in northern hemisphere from Europe to Japan, East Africa and India experienced heavy flooding

Extreme weather events in the UK (mini case studies/examples)

• March 2018, 'Beast from the East' brought 50 cm of snow, major disruption to traffic and schools

• July 2014, thunderstorms struck southern and central England, lightning strikes caused power cuts and delaying flights

• 2018 one of the hottest summers with temps of 35 degrees in Kent

How is the weather in the UK becoming more extreme?

Temperature

• UK's 10 warmest years all occurred since 1990, 2018 was the joint hottest summer on record.

• cold weather events more frequent too -+ December 2010 was the coldest month for over 100 years

Rainfall

• more rainfall records broken between 2010-2014 than in any decade

• major flooding events more frequent over the past 10 years

What are the impacts of extreme weather in the UK?

• schools shut

• damage to property

• pressure on services

• homelessness