Chapter 3 - Weather Hazards

Helps to explain the location of world climate zones and the distribution of weather hazards

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

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

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

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.

Strong high altitude currents of air

Polar cell, Ferrel cell, Hadley cell

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

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

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

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

Precipitation is low in polar regions and mainly falls as snow. The cold air has a limited ability to hold water vapour

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

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

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

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

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

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

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

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

1-2 weeks

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

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

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

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

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

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

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

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.

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

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

Devastinh damage, major damage to roof or removal

Electricity and water will be unavailable for several days to weeks after storm passed

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

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

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

The wealth of country

How much destruction

Help available from other countries, organisations and charities

Allows predictions to be made which can save lives and reduce impact

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

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

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

Is costly and time consuming, especially if the path of tropical storm does not pass area they live

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

Prepare disaster supply kits

Having fuel in vehicles

Knowing where official evacuation shelters

Storing loose objects

Planning with family what to do

It's damage done to societies that make these event hazardous

Main types of hydro meteorological hazards: storms, flooding, drought and extreme cold weather

Caused by heavy rainfall or strong waves brought by a depression

May also trigger landslide as a secondary hazard

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

High intensity Rainfall brings flash flooding especially on steep slopes

A long period of steady rainfall gradually saturates the catchment soil

Intense rainfall collects in hollows and depressions where homes are located

U.K. Regularly hit by depressions which bring heavy rainfall and trigger river floods

A tornados is a rotating column of spiralling sit whose formation is triggered by strong heating of the ground

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

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

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

Actions people take to increase their human resilience to hazards

Taken to protect communities

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

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

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

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

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

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

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

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

The frequency and magnitude of winter river flooding has increased since 1980s

Some predict uk river will flood more in future winters

Not sure if evaporation has increased but temp has risen by 1 C

Evaporation will increase due to higher air temps causing more droughts