Chapter 3 - Weather Hazards Flashcards
What’s global atmospheric circulation
Helps to explain the location of world climate zones and the distribution of weather hazards
What’s the most important influence on worldwide variations in climate/ tell me about how sunlight affects the climate
Latitude, because the curved surface of the earth, the equator receives much higher insolation that the polar latitudes - where’s as at low latitudes, sunlight is more highly concentrated
As a result, air at the equator is heated strongly - it becomes less dense and rises to high altitude, this creates a global climate zone of low pressure, the equatorial zone
After rising, the air spreads out and begins to flow towards the north and south poles
In low insolation received at polar latitudes result in colder, dense air and high pressure
As the air sinks towards ground level, it spreads out and flows towards the equator
What’s a convection cell
The low pressure belt at the equator and the high pressure belt at the poles provides the basis for a simple convection cell to operate
What’s the Hadley cell
The areas of high pressure at the tropics of cancer and Capricorn, air sinks towards the ground there and as it descends the air warms. The result is high pressure and hot, dry desert conditions. This circulation of air between the tropics and equator is the Hadley cell
What’s global circulations
Involves 3 cells Becuase the earth rotates on its axis , the movement generates strong, high altitude winds which wrap around the planet like belts
These winds flow towards the east, as the earth spins and interact with the convection cells.
What are jet streams
Strong high altitude currents of air
What are the global convection cells
Polar cell, Ferrel cell, Hadley cell
How is precipitation influenced by global pressure and surface winds at the equator
Rainfall is high and constant throughout the year near the equator. As hot air rises, it cools slightly. Water vapour is converted into droplets of conventional rain
How is the intertropical convergence zones precipitation affected by global pressure and surface winds
It’s a low pressure zone, air rises and triggers bursts of torrential rain. Sometimes the area grows a wave of low pressure which extends further than usual. Tropical storms develop along these waves. Once they gain energy, they can travel even further away from the equator
How is rainfall affected by coastal areas in Europe by global pressure and surface winds
Rainfall often higher due to movement of the jet stream over Atlantic. Rain bearing weather systems called depressions or cyclones follow the jet stream, often bringing stormy conditions to the uks west coast
How is rainfall affected in the tropics by global pressure and surface winds
Rainfall is often low around the tropics of Capricorn and cancer. Dry air descends there as part of the Hadley cell, resulting in arid conditions
Tell me how rainfall is affected in the polar regions by global pressure and surface winds
Precipitation is low in polar regions and mainly falls as snow. The cold air has a limited ability to hold water vapour
What are tropical storms
Are a natural hazard
Occurs when warm air rises to create an area of intense low pressure, much lower than depressions experienced in the U.K.. As the warm moist air reaches high altitudes, powerful winds spiral around the calm central point , creating the “eye of the storm” and the warm air cools and condenses into heavy rainfall and thunderstorms
How are names of tropical storms made
They are alphabetical and alternate in gender, more recognisable and engaging for public when given names rather than coordinates. Names repeat every 6 years unless a large loss of life or cost In damage would make it insensitive to repeat it
What are tropical storms called
They are called differently deepening on their location
Hurricanes in Atlantic and eastern Pacific oceans
Typhoons in the west of the North Pacific Ocean
Cyclones in the Indian and South Pacific oceans
Where do tropical storms occur
In the tropics where the intertropical convergence zone is - broadly south of the tropic or cancer and north of the Tropic of Capricorn
Found in areas of low latitude - between 5 and 30 degrees north and south of equator
Here a higher insolation means temperatures are higher than at the poles
Tell me the conditions for a tropical storm to form
Sea must be about 27 C and a depth of 60-70 Metres
This provides the heat and moisture that causes the warm air to rise Rapids in this low pressure region. Latent heat is then released which powers the tropical storm . The warmest seasons are between summer and autumn which is most typical for tropical to develop
There is low wind shear (which remains constant and does not vary with height) so that the tropical storm clouds can rise to high levels without being torn apart
They don’t develop on along the equator because the Coriolis effect is not strong enough here for strong tropical storms to spin
How does a tropical storm form
Air is heated above the surface of warm tropical oceans, the warm air rises rapidly under the low pressure conditions
The rising air draw up more air and large volumes of moisture from the ocean, causing strong winds
The Coriolis effect causes the air to spin upwards around a calm central eye of the storm
As the air rises, it cools and condenses to form large, towering cumulonimbus clouds which generate torrential rainfall. The heat given off when the air cool powers the tropical storm
Cold air sinks in the eye, therefore there is no cloud, so it’s drier and much calmer
The tropical storm travels across the ocean in the prevailing wind
When the tropical storm meets land it is no longer fuelled by the source of moisture and heat from the ocean and so it loses power and weaken, the air pressure and temperature rise. Wind and rainfall subside
Why does a tropical storm spin
The Coriolis effect bends and spins the warm rising air.
Hurricanes in the northern hemisphere bend to the right, which causes the clouds to swirl anti clockwise whereas cyclones in the Southern Hemisphere swirl In a clockwise direction
What direction do tropical storms travel
Travel from east to west due to the direction the earth spins
When they hit land, they lose their energy source from the sea that powered them - friction also allows them to slow down and as they slow doe they change direction
How long does an average tropical storm live for
1-2 weeks
What is the Coriolis effects
Wind blows from areas of high pressure to areas of low pressure, as the earth rotates it causes wind to bend because the earths curvature and so the earth spins faster at the equator and difference in speed means that wind bends as it blows across the earth
How could climate change alter the conditions that cause tropical storms to formed
As the temperature increases, sea levels will rise due to thermal expansion. The impact of rising sea levels will mean storm surges are expected to become higher
A Warmer atmosphere will mean the air can hold more moisture. So heavy rainfall is expected to increase. Therefore flooding during a tropical storm would be more destructive
How does climate change affect the intensity of tropical storms
There is evidence of warmer oceans and the intensity of tropical storms - and expected to become more severe
Every 1 C increase in sea surface temperatures will mean a 3-5 percent increase in wind speed
How does climate change affect the frequency and distribution of tropical storms
Frequency to stay same or decrease
By will be more severe storms, and category 1-3 storms will decrease
The regions where tropical storms are experienced are not expected to change significantly as a result of climate change
How does the uncertainty of tropical storms change due to climate change
Predicting impacts is unreliable as the rate of and impact of climate change in the future is uncertain
Potential risk to like and property has already increased due to population growth and building in coastal locations even without factoring in climate change
What are the effects of a tropical storm
Landslide and tornadoes can also be caused by tropical storms
Wind speeds are at least 119kM an hour they can demolish houses across ,whole towns and villages, electricity power lines
Flooding caused by heavy rain from storm surges - can be up to 5 metres
Aid is hampered as roads are flooded
Water supplies can be contaminated with seawater, sewage and industrial waste - increase risk of waterborne diseases such as cholera
How are tropical storms measured
Measured using the saffir-Simpson hurricane wind scale
It’s based on when’s speed
The higher the category scale 1-5 the higher the intensity of a tropical storm
What are the responses to a tropical storm
Evacuation to higher ground or even to emergency storm shelters
Distributed emergency food and water To survivors, aid may be hindered if roads have become blocked by debris or fallen trees or flooded.
Tell me about a wind category 1 storm
Some damage to well constructive roofs, large branches of trees will snap, power outraged could last several days
Very dangerous winds will produce some damage
Tell me about a wind category 2 storm
Well constructed roofs will have major roof damage, shallow rooted trees will be snapped or uprooted
Near total power is lost and power outrages could last from several Days to weeks
Extremely dangerous winds will cause extensive damage
Tell me about a wind category 3 storm
Devastinh damage, major damage to roof or removal
Electricity and water will be unavailable for several days to weeks after storm passed
Tell me about a wind category 4 storm
Catastrophic damage will occur
Loss of most of the roof structure
Most trees will be snapped or uprooted
Most of area will be uninhabitable for weeks or months
Tell me about a wind category 5 storm
Catastrophic damage will occur
Frames of houses destroyed, total roof failure, fallen Trees, power outraged will last for weeks week months and area will be uninhabitable for weeks to months too
What’s sustainable development
After initial relief effort, these are long term repainted that take longer to implement but have longer lasting impacts
Projects include repairing damage to existing buildings, infrastructure and businesses
Investing In methods of protection and prediction in storms such as a new warning system for storm surges or new sea defences
How what the speed to start long term responses depend on
The wealth of country
How much destruction
Help available from other countries, organisations and charities
What does monitoring tropical storms mean
Allows predictions to be made which can save lives and reduce impact
How can satellites monitor tropical storms
There’s a classic cloud pattern associated with tropical storms that satellites can monitor
The global precipitation measurement satellite measure preoccupation every 3 hours between latitudes 65 degrees north and south of equator to identify the high altitude rainclouds
How can aircraft monitor tropical storms
They can collect air pressure, rainfall and wind speed data, they release drop sondes (sensors) which send measurements every second by radio back to the aircraft
On board radar and microwaves help scientists to understand more about the formation of tropical storms to improve forecasting models
Can tropical storms be predicted
All available weather data is fed into supercomputers which run models to predict the path and intensity of tropical storms
Can now give 4 days warning and a location within 400km accuracy
Cyclone Phailin predicted and 1.2 million evacuated
What’s the problem with evacuation
Is costly and time consuming, especially if the path of tropical storm does not pass area they live
How can we protect ourselves from tropical storms
Areas can be reinforced to reduce damage caused by winds- mitigation
Install hurricane straps between the roof and walls
Install storm shutters on Windows
Install an emergency generator
Tie down windborne objects
Reinforce garden doors
Remove trees close to buildings
Coastal flood defences such as levées and floodwalls reduce impact on storm surge
How can planning reduce risks
Prepare disaster supply kits
Having fuel in vehicles
Knowing where official evacuation shelters
Storing loose objects
Planning with family what to do
What’s extreme weather
It’s damage done to societies that make these event hazardous
Main types of hydro meteorological hazards: storms, flooding, drought and extreme cold weather
Tell me about general flooding in the U.K.
Caused by heavy rainfall or strong waves brought by a depression
May also trigger landslide as a secondary hazard
Tell me about coastal flooding
A deep depression brings a storm surge to a major river estuary
Strong winds funnel coastal water into the mouth of a river
In 1953, 300 people died when a storm surge hit the Thames estuary
Tell me about river flash flooding
High intensity Rainfall brings flash flooding especially on steep slopes
Tell me about slow onset river flooding
A long period of steady rainfall gradually saturates the catchment soil
Tell me about surface water flooding
Intense rainfall collects in hollows and depressions where homes are located
Tell me about storm events in the uk
U.K. Regularly hit by depressions which bring heavy rainfall and trigger river floods
Tell me about tornadoes in the uk
A tornados is a rotating column of spiralling sit whose formation is triggered by strong heating of the ground
Tell me about droughts in the uk
It’s an extended period of low or absent rainfall relative to expected average for a region
15 days with less than 0.2mm of rain means there may be insufficient moisture for average crop production
Tell me about extremes of cold water in the U.K.
Cold conditions take over if depressions are not passing over the uk as usual
Risks include
Frost - crops and cattle may not survive below -10 C
Freezing conditions mean trains can be cancelled
Blizzard conditions - transport grinds to a halt, creating costly airline delays
How could we manage the risk of extreme weather in uk
Use Twitter and other social media to alarm others of damage
Future proof their homes by very sensibly having stone tiles rather than carpets in their ground and basement rooms
What are bottom up actions
Actions people take to increase their human resilience to hazards
What are top down actions
Taken to protect communities
What top down actions can we take for droughts
A hose pipe ban can be put in place - even send out hose pipe patrols
Water supplies to houses are turned off and members of public take their then queuing in the street at standpipes
Encourage people to have a water meter fitter and do more to repair old water pipes
What top down actions can be taken to storms
The U.K. met office is trying to improve weather predictions
Severe weather warnings can be issued using social media and social media
Airlines and rail companies cancel their services when there are very strong winds
What top down actions can be taken for floods
The Thames barrier was completed to avoid storm surges
The environment agency constantly monitors ground moisture levels in river basins so EA can make accurate flood predictions to allow evacuation
Any new housing on floodplains face higher insurance bills - deter construction
What top down actions can we take for cold water
Clear roads of snow and ice
Make announcements in media warning people to take care while in blizzard conditions
Charities for elderly raise awareness about more health risks for old people in cold conditions - work to raise public awareness of issue
How has climate change changed storm frequency
There has been an increase in extreme rainfall since 1980s as the Atlantic Ocean has warmed and rain bearing depressions will be
Gaining more moisture and energy
What does temperature record tell us about drought frequency
U.K. Temps have increased by 1 C since 1980 - however in the graph showing temp change the spikes shown don’t all correspond with drought where the spikes are a higher temp as rain deficiency is needed to
What are the extreme weather predictions for the future
Some suggest a global Temp rise of 2-3 C in the 21st century
If this happens U.K. Could face warmer and wetter winters - more rain bearing depressions
Risk of extreme flooding and high winds will increase
A global temp increase of 4-5 C would melt a lot of land and sea ice in artic, colder water would pour into the North Atlantic which would cause unknown effects but with a warmer world the U.K. Could be left facing more extremes of cold water
Tell me about the current and predicted precipitation
No change in annual uk total but more winter rainfall has fallen in heavy events since 1980s
But in future will become more seasonal but annual uk total will stay the Same
Tell me about the current and predicted changes in river flow
The frequency and magnitude of winter river flooding has increased since 1980s
Some predict uk river will flood more in future winters
Tell me about current and future evaporation changes
Not sure if evaporation has increased but temp has risen by 1 C
Evaporation will increase due to higher air temps causing more droughts
