Weather hazards + climate change

• Incoming solar radiation


  • Covers a larger area and thicker atmosphere leading to colder temperatures
  • Covers a smaller surface area and thinner atmosphere leading to higher temperatures
• Albedo effect


  Light coloured surfaces reflect the solar radiation back; ice and snow are white surface that reflect heat
• Low pressure


  • Air is heated and rises as it is less dense, transfers heat into the atmosphere, cools, condenses and causes clouds and rain
  • Less air at the surface, so low pressure
• High pressure


  • Air cools and becomes more dense, falls and warms due to the heat of the ground, leaves clear, dry skies
  • More air at the surface, so high pressure
• When high pressure is on the ground

  The wind moves to the low pressure
• Coriolis effect


  Winds are deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere due to the Earth's rotation
• The global atmospheric circulation model

  1. Warm air rises at the Equator, creating low pressure and rain/clouds

  2. Cooler, dry air moves away from the Equator and sinks at 30°, creating high pressure and clear skies

  3. Warm air moves towards the poles as westerlies

  4. Warm air meets colder air from the poles, forcing the warm air to rise and create low pressure and rain

  5. Cool air sinks at the poles, creating high pressure and clear, dry skies
• Ocean currents


  • Large scale movements of water that transfer heat energy from warmer to colder regions
  • Surface currents are caused by winds that transfer heat away from the Equator
  • Deep ocean currents are driven by differences in water density
  • When water freezes at the poles, the surrounding water gets saltier and denser, causing it to sink and creating a current of warmer water flowing in at the surface
• Thermohaline circulation


  The cycle of the warmer water being cooled and sinking, continuing the flow of currents
• Evidence of climate change

  1. Ice cores - analyse gases trapped in layers of ice to show temperature change over 400,000 years

  2. Tree rings - thicker rings in warm and wet conditions provide evidence of climate over 10,000 years

  3. Pollen records - preserved pollen in sediment shows species living at that time

  4. Historical sources - global temperatures accurately measured since 1850s, historical records like diaries and paintings show past climate
• In the last 400,000 years there have been big variations in temperature compared to today's average, with glacial periods of extended cold and interglacial periods of extended warmth
• It took 5000 years for temperatures to increase by +1.2°C, but since the Industrial Revolution global temperatures have increased by +1.2°C in 140 years
• Milankovitch cycles


  • Eccentricity - Earth's orbit changes from circular to oval every 96,000 years, leading to glacial periods when furthest from the sun
  • Tilt - Earth's tilt on its axis changes every 41,000 years, affecting the seasons
  • Precession - Earth wobbles on its axis every 22,000 years, changing the direction it faces the sun
• Sunspots


  Changes in the sun's solar activity, with more sunspots leading to more solar energy and warmer temperatures, occurring in an 11 year cycle
• Little Ice Age


  Period of reduced sunspot activity in the 17th and 18th century, leading to cooler temperatures in London
• Volcanic activity


  Large eruptions can change the Earth's climate by releasing ash into the atmosphere
• The enhanced greenhouse effect

  1. The sun's short wave energy passes through the atmosphere to Earth

  2. Earth radiates long wave energy out into the atmosphere

  3. Some energy escapes back into space

  4. Some energy is trapped by greenhouse gases and re-emitted back, warming the Earth's climate

  5. Increased greenhouse gas levels from human activities like burning fossil fuels and deforestation trap more energy and warm the climate further
• Causes of the enhanced greenhouse effect

  • Industry - increased demand for consumer goods
  • Energy - growing demand for electricity and transport fuels
  • Transport - more people using cars and air travel
  • Farming - population growth leading to more intensive agriculture
• Climate change


  • Warmer temperatures cause sea levels to rise due to water expansion and melting of glaciers and ice sheets
  • Warmer temperatures and more droughts negatively affect farming, leading to food shortages and malnutrition
• Climate


  The long term (30 years) average weather conditions for large areas
• Weather


  The daily condition of the atmosphere at a particular time and smaller location
• Types of rainfall


  1. Convectional - warm air rises, cools and condenses to form clouds and rain

  2. Relief - warm moist air is forced to rise over high areas, cools and condenses to form clouds and rain

  3. Frontal - warm air is forced to rise over a cold front, cools and condenses to form clouds and heavy rain
• Air masses in the UK

  • Polar maritime - cold air and showers
  • Arctic maritime - very cold in winter
  • Polar continental - cold, dry winters and warm, dry summers
  • Tropical continental - dry settled weather and hot summers
  • Tropical maritime - wet, warm, windy weather
• Continentality


  The difference in temperature between coastal and inland areas, with coastal areas having less temperature variation throughout the year
• The north and west of the UK are cooler than the south and east, with the west having higher rainfall due to the prevailing south-westerly winds
• Temperatures are lower and rainfall is higher in mountainous areas compared to lowland areas
• Tropical cyclone in a developing country

  Typhoon Haiyan in the Philippines
• When Typhoon Haiyan occurred


  November 7 2013
• Tropical cyclone in a developed country

  Hurricane Sandy in the USA
• When Hurricane Sandy occurred

  5 October 2012
• Drought in a developing country

  Ethiopia
• When the drought occurred in Ethiopia

  2016
• Drought in a developed country
• Responses to tropical cyclone in a developing country
• Responses to tropical cyclone in a developed country
• Responses to drought in a developing country
• Responses to drought in a developed country