Weather and climate

Terms in this set (20)

Anticyclones affecting UK:

• Anticyclones are areas of high atmospheric pressure, caused by a large mass of falling air. The air falls from the upper atmosphere, and warms in its way down. This causes the humidity to decrease because air masses can hold moisture as they get warmer.

• Anticyclones cause different weather conditions in winter and summer

• Summer anticyclones:
o Clear skies, which allow the maximum amount of insolation, producing temperatures of over 25°C in the daytime
o Significant radiation loss by night can lead to short-lived temperature inversion and dew and mist during the morning
o The differences in the rate of warming of the sea and land can produce land and sea breezes, while onshore winds can create advection fog
o Conditions for a heatwave if anticyclones deflect low-pressure areas to the north.
o Thunderstorms and localised uplift can result from sustained and intense heating when the air has high humidity

• Winter anticyclones:
o Sun is low in the sky and less insolation is available to warm the British isles, leads to low temperatures in the day from below freezing to maximum of 5°C
o Surface cooling frequently gives rise to radiation fog and frost which may persist because of the weak sunshine during the day. It's generally clear skies by day and night
o PC air from central Asia and Europe can bring heavy snowfall in eastern regions of the UK
o Blocking anticyclonic cells in Europe can deflect warmer depressions and bring dry, freezing conditions to Britain. Causing low, sharp temperature inversions leading to persistent cloud, sometimes known as anticyclonic gloom.
o High levels of atmospheric pollution in urban areas, caused by a combination of subsiding air and lack of wind.
Evidence of responses to global warming:
• Kyoto Protocol:
o International agreement formed in December 1997 and 190 countries joined the agreement.
o In 2008, the UK government pledged to cut carbon dioxide emissions to 80% of the 1990 level by 2050.
o Russia agreed to the treaty in November 2004 and it became legally binding for them in February 2005.
o 55 countries to the Convention ratified the Protocol, including countries responsible for at least 55% of industrialised countries carbon dioxide emissions in 1990.
o Carbon credits ensure that countries are given a limit on the emissions they can produce, if they produce less they can sell the surplus carbon credits, if they produce more they need to buy more credits.
o However four countries with high emissions (USA, Australia, China and India) didn't sign up to the original agreement, as they felt it would affect their economies and slow their rate of growth.

• Carbon Capture and Storage (CCS) is a technology designed to reduce climate change by reducing emissions from power stations. It has the potential to reduce emission from power stations by 90%. However it does use fuel and increase the cost of energy

• In the UK, the Carbon Trust was granted £65 million from the government over 5 years to help provide loans to small and medium-sized businesses investing in improved energy efficiency

• In the UK, recycling prevents the release of 10-15 million tonnes of carbon dioxide every year. This is like taking 3.5 million cars off the road every years.

• DEFRA in the UK reports annually on levels of emissions of greenhouse gases and the success of measures set out in the climate change programme.
Air quality in urban areas:

• Air quality of urban areas is poorer than in the surrounding countryside. Cities may have up to 7 times more dust particles in their local atmosphere.

• Burning of fossil fuels particularly from vehicular and industrial sources, is the dominant factor in causing bad air quality
• Urban areas have as much as 200 times more sulphur dioxide, 10 times more nitrogen dioxide and twice as much carbon dioxide than rural areas.

• Pollutants produced by human activity include sulphur oxide, carbon monoxide and carbon dioxide

• Vehicle exhausts produce 80% of fine particles in urban areas

• Pollutants tend to increase cloud cover and precipitation and cause photochemical smog, all of which produce higher temperatures and reduce sunlight.

• Smog was a problem for London in the 1950's, because the Thames basin is prone to radiation fog, as it is sheltered from westerly winds. A mixture of smoke and fog

• In December 1952, smog in London was responsible for more than 4,000 deaths.
• Photochemical smog forms when sunlight hits various pollutants in the air and forms a mix of chemicals that can be very dangerous. It's extremely common in cities with sunny, warm and dry climates, such as Los Angeles

• Responses to air pollution:
o The 1956 act in London introduced smoke free-zones and this slowly cleaned up the air
o In Central London the congestion charge has reduced traffic and emissions by up to 15% since 2003
o In Athens an area of about 2.5km² in the centre of the city was declared traffic-free
Structure of the atmosphere:

• The troposphere:
o The zone lies closest to the Earth, it about 12km up on average and the most weather processes take place here
o Air temperatures drop by 6.4°C with every 1,000m gained in height.
o Wind speeds increase with increasing altitude as frictional drag with the surface plays a diminishing role
o This is the most unstable layer and contains most water vapour and particulate matter
o The end of the troposphere is marked by the tropopause, an isothermal layer where temperature remains constant as altitude increases. It marks the upper limit of the zone of weather and climate

• The stratosphere:
o This comes after the troposphere and extends from 12km to 50km up.
o Here there is a steady increase in temperature (temperature inversion) as a result of absorption of solar radiation by the ozone layer
o The ozone layer absorbs much incoming UV radiation that would be harmful to humans
o The atmosphere is noticeably thinner in this zone as pressure decreases with height and there is a lack of vapour and dust
o Wind speeds increase with height towards the stratopause, another isothermal layer

• Mesosphere:
o The mesosphere extends from around 50km to 85-90km up.
o Temperature declines rapidly in this zone to -90°C, as there is no water vapour or dust to absorb radiation
o It features very strong winds, approaching 3000 km/hr and culminates in another isothermal layer called the mesopause.

• Thermosphere:
o The thermosphere extends from 85-90km to around 1000km up, largest zone.
o Temperatures start to rise again at a constant rate up to as much as 1500°C, due to the absorption of UV radiation by atomic oxygen found at this altitude.
o Got its name from the increase in temperature
Responses to pollution in cities:

• Clean Air Acts
o After the London pea-souper of 1952, the government decided legislation was needed to prevent so much smoke entering the atmosphere. The act of 1956 introduced smoke-free zones into the UK's urban areas and this policy slowly began to clean up the air.
o In the 1990s, for example, very tough regulations were imposed on levels of airborne pollution, particularly on the level of PM10s in the atmosphere.
o Local councils in the UK are now required to monitor pollution in their areas and establish Air Quality Management Areas where levels are likely to be exceeded. Some have planted more vegetation to capture particulates on leaves.

•Vehicle control in inner urban areas
o A number of cities have looked at ways of controlling pollution by trying to reduce the number of vehicles that come into central urban areas. In Athens, for example, the city declared an area of about 2.5 kmr in the centre traffic free.
o Many British towns and cities have pedestrianised their CBDs. In London, attempts to control vehicle numbers have included introducing a congestion charge which means vehicle owners have to pay if they wish to drive into the centre. The Greater London Low Emission Zone is an extension of this.
o In Central London the congestion charge has reduced traffic and emissions by up to 15% since 2003
o In Mexico City, the city council passed driving restriction legislation known as the Hoy no Circula (don't drive today). This bans all vehicles from being driven in the city on one weekday per week, the vehicle's registration number determining the day.

• More public transport:
o Attempts have been made to persuade people to use public transport instead of cars.
o Such schemes have included Manchester's development of a tram system (Metrolink), the development of bus-only lanes into city centres, the growth of park-and ride schemes in many British cities and the encouragement of car sharing schemes.

• Zoning of industry:
o Industry has been placed downwind in cities if at all possible and planning legislation has forced companies to build higher factory chimneys to emit pollutants above the inversion layer.

• Vehicle emissions legislation:
o Motor vehicle manufacturers have been made to develop more efficient fuel-burning engines and to introduce catalytic converters which remove some of the polluting gases from exhaust fumes.
o The switch to lead-free petrol has also reduced pollution.
The Cockermouth floods, November 2009 (responses):

• Construction work by the army to build a new temporary footbridge crossing the River Derwent in Workington, uniting communities cut off on the north and south side of the river.

• By January 2010, 78 of Cockermouth's 225 businesses were trading from their original premises and a year after the floods, only 30 remained closed. In September 2010, the Derwent House GP surgery re-opened after moving to temporary accommodation.

• Mobile centres in Keswick and Workington provided support to communities cut off by the floods. A newsletter offering advice and information was distributed via the flood support centres.

• A temporary rail station built by Network Rail just north of the River Derwent to improve links on the two sides of the river.

• Extra bus services provided for school children and the public. Health services maintained throughout the disruption and temporary clinics set up to help people.

• Support for businesses has also been established. The North West Regional Development Agency (NWDA) pledged up to £1 million for small businesses and is working closely with Cumbria County Council to assist businesses which suffered.

• Temporary accommodation organised for many small businesses displaced through the floods.

• Charitable funds and grant aid established for affected individuals, families and community organisations suffering hardship through the floods.

• The Cumbria Recovery Fund provided significant financial help (£774 per household) to hundreds of homeowners faced with costly repairs to flood-damaged properties. By November 2010, 85 - 90% of residents from Cockermouth's 691 flood-damaged homes had returned permanently.