Ocean Currents: Warm ocean current: North Atlantic Drift (causes mild conditions in the winter)
Prevailing Winds: North Atlantic Drift coincides with South-Westerly prevailing winds in the UK. Mild but damp climate with winds mostly approaching the UK from a war ocean
Maritime Influence: Air over the UK tends to be humid because it's an island. High amounts of rainfall and cloudy weather conditions.
Continentality: Inland areas are drier - insolation heats up the land quicker in the summer. And land loses heat more rapidly in winter.
Altitude: Upland areas record higher amounts of precipitation. Temperatures decrease with altitude.
Temperature in January
Warmest plaes are to the West and the South where the N.A. Drift has a big influence. Coldest areas are in the North where the sun is at a lower angle in the sky. Cold over mountains because of altitude. Cold polar air moving south affects the North. Sea warms up the costal fringe.
Temperature in July
Warmest places in South - warm air from southern Europe nudges into the south of the UK
Precipitation or Rainfall
South-Westerly winds explain high precipitation in West. Driest areas in the East sheltered by uplads from moist Atlantic winds.
Highest sunshine values in the South and East. Anticyclones from South bring stable and cloud-free conditions affect coastal areas in the South. Upland areas have less Sunshine.
- Warm front stretches through the North Sea
- Cold front stretches through the centre of England
- Warm front: conditions become cloudier and a period of rain sets in
- Behind the warm front: Temperature increases in the warm sector. Cloudy + drizzle
- Cold front: Short period of heavy rain + strong winds
- Behind the cold front: Temperature drops sharply and rain stops but showers may occur.
Area of high atmospheric pressure caused by air sinking towards the ground surface. The sinking air stops pockets of air from rising. Rain is unlikely and conditions are clear + sunny. Winds in an anticyclone in the Northern Hemisphere circulate in a clockwise direction.
In the winter: Clear, cloudless conditions - sunny and crisp days and frosty nights. Air over the UK is moist so under cold conditions there's fog. These overcast conditions can last several days at a time.
In the summer: Sun is more powerful and burns off any low cloud and fog. Warm sunny days.
Early February. Moist, low temperatures, little wind: Isobars are far apart. Dull conditions w/mist and fog. If the air had been drier: conditions wouldve been cold, crisp and sunny days.
Little cloud in the centre, more cloud at the edges. Lack of cloud in summer means high temperatures. Easterly winds bring warm and dry air. Cooler and cloudier in N.E coast
16 August 2004 in Cornish village of Boscastle - 200mm of rain fell in 24 hours. River Valency burst its banks. No one was killed but a number of people had to be airlifted to safety.
Floodwaters spread across the car park before surging down the narrow streets towards the harbour. Many cars were picked up and carried by the floodwaters. Trunks and large branches and cars smashed into bridges and buildings.
- 58 buildings flooded
- 25 businesses destroyed
- 84 cars wrecked and 32 lost
- 15 million pounds of costs
- Dehumidifiers used to dry things
MET Office has 3-tier system of warnings:
- Advisory of servere extreme weather
- Early warnings of severe weather when there's > 60% chance it'll occur
- Flash warning of severe weather conditions when there's a > 80% chance it will occur in the next few hours.
Global Warming Evidence
Instrument Readings: Warming trend in the last few decades. Average global temperatures have risen by 0.74ºC during the last 100 years.
Glacier Retreat: 25% of global mountain glacier ice could disappear by 2050.
Arctic Ice Cover: Over the last 30 years, Arctic ice thinned to almost half its earlier thickness. As it continues to thin, less solar radiation will be reflected back into space. Instead, the sea will absorb more radiation, increasing temperatures further.
Ice Cores: Water molecules and trapped air can be analysed to detect subtle changes in temperature and atmospheric gas concentrations at the time when each layer of snow fell.
Early Springs: Seasonal shifts with spring arriving earlier. Winters are less severe.
Causes of Global Warming
Carbon Dioxide: 60% of the greenhouse effect
- Burning fossil fuels in industry and power stations to produce electricity
- Car exhausts
- Burning wood
Methane: Very effective in absorbing heat - 20% of greenhouse effect
- Decaying organic matter in landfill sites and compost tips
- Rice farming, farm livestock
- Burning biomass
Nitrous Oxides: 300x more effective in capturing heat than Carbon Dioxide
- Car exhausts, power stations producing electricity
- Agricultural fertilisers
- Sewage treatment
Advantages & Disadvantages
- Frozen regions may be able to grow crops in a milder climate
- Canada's North-West passage may become ice-free and can be used by shipping
- Energy consumption may go down as temps incease
- Fewer deaths and injuries due to cold weather
- Longer growing season in rich agricultural areas such as Europe and N.America - more food!
- Higher sea level may flood low-lying areas such as Bangladesh, Myanmar and Netherlands threaten the lives of 80 million people
- Islands such as the Maldives may completely disappear
- Parts of Africa may become drier and more prone to draughts
- Cereal yields would decrease
- 280 million people at risk from malaria
- Tropical storms may increase
- Species may become extinct
- Loss of glaciers threaten agriculture and water supply in India, Nepal and China
Responses to Global Warming
- Conserving energy
- Walking or cycling
- Reducing waste
- Buying organic food
- Reduce chemical fertilizers
- Taxes on gas emissions
- Encouraging recycling and waste reduction initiatives
- Power stations fitted with filters to reduce emissions
International: Kyoto Protocol - 16 February 2005 and Carbon credits
Hurricanes can be triggered and tend to form:
- Over warm water which explains why they're found in the Tropics
- In summer and autumn when sea temperatures are at their highest
- Greater latitudes - any closer to the equator there isnt enough spin from the roation
- Tropical regions of severe air instability where air's converging on the surface and rising rapidly
Effect of Hurricanes:
- Strong winds with sustained wind speeds - roofs blown off, power lines torn, crops damaged
- Heavy rainfall - widespread flooding as rivers burst its banks + landslides
- Storm surge - area of low pressure as it moves over the sea.
2005 - formed over the Bahamas and then passed over Florida. Intensified in the Gulf of Mexico. Strongest winds recorded were 280 kph. Levees failed and there was widespread flooding.
- 1836 dead
- 100s of 1000s displaced from their homes - many evacuated
- 3 million people w/out electricity
- 80% of New Orleans flooded
- $89 billion
- All services affected
- Rescuing people from floodwaters, treating injured, providing food, water and shelter
- Massive rebuilding of New Orleans
- Strengthening of levees
- Floodwater became severely polluted
- Physical changes to Mississippi delta
- 80% evacuated
2008 - Developed in the Bay of Bengal in April and made landfall in the South-West of Myanmar.
- 140,000 dead
- 3 million homeless
- 95% homes destroyed
- 1.5 million people affected
- $10 billion
- Government refused to admit foreign aid and relief workers for several weeks
- Identification and burial of dead
- Treating injured
- Rebuilding homes and workplaces
- Reclaiming farmland from salty water
- Rebuilding services
- Burst sewage pipes caused population
- Most people had no idea that the cyclone was approaching