Weather and Climate and Associated Hazards (Part 2)

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Created on: 27-03-14 11:37

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Weather and Climate and Associated Hazards (Part 2)
- Activity Two: The Climate of the British Isles
  - Summer Temperatures
    - The sea takes a long time to heat up in summer giving a cool summer
    - Temperatures are lower over mountainous areas
    - Warmer because the suns rays are more isolated
  - Winter Temperatures
    - Warm and cold air masses converge causing snowfall/gail force winds
    - Temperatures decrease from west to east because the warm North Atlantic Drift hits the UK in the south west
  - Annual Rainfall
    - Rainfall decreased from east to west
    - Convectional rainfall
    - Low pressure moves south west to north east, as a result it is wetter in the south west
    - More rainfall in the south west due to prevailing winds bringing Atlantic moist air
- Activity Three: Identity and Explain the Air Masses which Influence the UK
  - What are the air masses?
    - Polar Maritime (PM)
      - From the polar region the air mass has had to travel over an ocean area and has therefore picked up a lot of moisture
    - Polar Continental (PC)
      - From the polar regions, it has travelled over land
    - Artic Maritime (AM)
      - Has travelled from the arctic over the ocean picking up moisture
    - Tropical Continental (TC)
      - Travels from North Africa overland picking up little moisture
    - Tropical Maritime (TM)
      - Travels from the tropics but forms over the sea so produces lots of moisture
    - What does this mean for the UK?
      - Polar Continental (PC)
        In winter, the air mass is cold so the airstream warms as it approaches Britain, causing it to become unstable. It brings very cold weather in winter and dry conditions in summer
      - Polar Maritime (PM)
        Starts off cold at its base as it moves towards Britain. Brings unstable cool and showery conditions
      - Tropical Continental (TC)
        Very stable; it brings hot and dry conditions
      - Tropical Maritime (TM)
        Mild wet weather in winter and warm damp weather in summer
      - Arctic Maritime (AM)
        Brings very cold temperatures and rain in winter
- Activity Four: Describe and Explain the Origin and Nature of Anticyclones
  - Anticyclone: An area of high atmospheric pressure that is slow moving and are dominated by subsiding air
  - Weather characteristics associated with anticyclones
    - High Pressure
      - Air sinking into one area, increasing the concentration of air in one area
    - Clear Skies
      - Warm air leads to evaporation, humidity decreases leading to no clouds
    - Hot in Summer
      - Intense insolation with a lack of clouds
    - Cold in Winter
      - Heat can not be trapped due to a lack of cloud cover
    - Light Winds
      - High pressure means wind is not slowing into the air resulting in light winds
    - Heat wave in Summer
      - Anticyclones move slowly and block out other weather systems causing heat waves
  - Fog
    - Radiation Fog
      - This occurs overnight when there are clear skies and there is radiation from the cold ground. As the ground cools, moisture in the air close to the ground and condenses forming fog
    - Advection Fog
      - When warm moist sir moves horizontally over a cooler land or sea surface it is cooled from below. If the temperature of the air cools below due point, condensation occurs and advection fog is formed
- Activity Five: Describe and Explain the Origins and Nature of Depression
  - The Formation of a Depression
    - Warm air constantly moves out of tropical areas, towards the poles. A warm front is the leading edge of a warm air mass (usually tropical maritime)
      - Cold air moves out of polar regions, towards the tropics. A cold front is the leading edge of a cold air mass (usually polar maritime)
        Where the air masses meet, the warm air heading towards the poles rises above the cold air because it is more dense
        The rising warm air reduces atmospheric pressure. Strong winds blow from surrounding areas of high pressure towards this area of low pressure the whole system starts to rotate
  - The Development of a Mature Depression
    - Warm air forms a bulge into the cold air
      - This is an an embryo depression
  - Weather Conditions associated with a Depression
    - Ahead of the warm front, its cool because the cold air is overhead. Thin cirrus clouds form high up
      - As the warm front passes it gets warmer. Nimbostratus clouds form producing light rain over a long period of time
        When the warm sector is overhead it is warm with no cloud and relief rainfall only
        As the cold front passes, temperatures reduces and cold air undercuts the warm air. This increases the uplift rate and forms cumulonimbus clouds. Causing heavy short downfalls of raim
  - Occlusions
    - As the cold front moves faster than the warm front it eventually catches the warm front to form an occluded front.
      - The warm sector is lifted completely up off the ground as it undercut by the cold front
        There is no warm air left to be uplifted so there is less rainfall. There is little condensation so cloud cover decreases. Wind speed also decreases
- Activity Six: Discuss the Processes and Impacts related to British Storms
  - The Impact of Weather systems on the UK
    - Positive Impacts of Depressions
      - Lots of rain - reliable water supply
        Irrigation/farming made easier
        Wind is used for renewable energy
    - Negative Impacts of Depressions
      - Predicting weather made difficult
        High winds cause damage
        Heavy rains cause flooding
        Distribution to sporting events
    - Positive Impacts of Summer Anticyclones
      - Heat waves in the south
        Good for seasonal businesses
        Boost for tourism
    - Negative Impacts of Summer Anticyclones
      - Droughts
        Roots breaking up
        Heat stroke
    - Positive Impact of Winter Anticyclones
      - Provides light relief
        Provides insolation for the ground
    - Negative Impact of Winter Anticyclones
      - Big freeze
        Heavy snow
        Illness/injury more common
        Elderly people are vulnerable
        Affects transport (flights/trains)
        Increased insurance claims
  - Storm Formation
    - Cold polar air meets warm tropical air
      - Creating the polar front and thus depressions
    - Rapid movement across the Atlantic
      - Driven by the polar jet stream
    - Maritime Air
      - Resulting in unstable rising air
    - Autumn storms due to warmth of ocean from summer heating
      - High moisture levels creating high rainfall
    - Steep pressure gradient
      - Creating very strong winds
  - The Great Storm (1987)
    - 18:00 15th Oct.
      - Calm winds and wind isobars
      - Warm front of depression, light rainfall only
      - MET OFFICE predicted heavy rainfall in the south only
      - Bay of Biscay (embryo depression)
    - 24:00 16th Oct.
      - Heavy rainfall due to cold front
      - Centre of depression over Cornwall
      - Warm sector covering southern UK
      - Strongest winds still over France
    - 06:00 16th Oct.
      - Centre has now passed
      - Very strong winds
      - Occlusion forming
  - Impacts
    - Physical
      - 15 million trees blown down
      - Broadleaf trees badly damaged
      - Non-native trees were hard hit
      - Orchard trees were devastated
    - Social
      - 18 deaths
      - Houses and cars damaged
      - People scared of high winds
      - 30 schools closed due to damage
      - Fire Brigade 6000 calls in 24 hours
    - Economic
      - Employed population struggled to work
      - Power cables and pylons damaged
      - Rail services disrupted
- Activity Seven: Understand How Climate is Influenced by Urban Areas
  - Temperature
    - Urban Heat Island Effect
    - Air pollution increases cloud cover. Allows shortwave radiation, traps outgoing radiation
    - Rock absorbs heat during the day which is released slowly at night
    - Heat from industries, buildings, vehicles and people
    - Higher thermal heat capacity (low albedo)
    - Reduced evapotranspiration means that more energy is available to heat the atmosphere
    - Changes over Time
      - Diurnal
        Daytime -0.6 higher
        
        Night-time - 3.5 higher
      - Seasonal
        Mean winter term 2 warmer
        
        Summer mean temp 5 higher
      - Park
        Lower temp / cooler due to light surface / more evapotranspiration
  - Precipitation
    - Air is unstable. Warmer air over urban area
    - Source of uplift. Temperatures. Tall buildings create more upward movement of air
    - A source of moisture. Individual emission increase amount of water vapour
    - High concentration of condensation nuclei
  - Wind
    - Reduction of wind spped
    - Buildings create frictional drag so average wind speeds are lower
    - Shelter on leeward sides of the buildings
    - Highest pressure on windward side of buildings
    - Turbulence occurs on leeward side
    - Bridgewater Place in Leeds caused the death of 1 man due to the venturi effect. This road is now closed when wind-speeds are predicted to be 45mph. Building will have large screens and baffle boards to deflect wind.
High pressure means wind is not slowing into the air resulting in light winds
Activity One: Describe and explain the major global climate controls
- Weather and Climate and Associated Hazards (Part 2)
  - Activity Two: The Climate of the British Isles
    - Summer Temperatures
      - The sea takes a long time to heat up in summer giving a cool summer
      - Temperatures are lower over mountainous areas
      - Warmer because the suns rays are more isolated
    - Winter Temperatures
      - Warm and cold air masses converge causing snowfall/gail force winds
      - Temperatures decrease from west to east because the warm North Atlantic Drift hits the UK in the south west
    - Annual Rainfall
      - Rainfall decreased from east to west
      - Convectional rainfall
      - Low pressure moves south west to north east, as a result it is wetter in the south west
      - More rainfall in the south west due to prevailing winds bringing Atlantic moist air
  - Activity Three: Identity and Explain the Air Masses which Influence the UK
    - What are the air masses?
      - Polar Maritime (PM)
        From the polar region the air mass has had to travel over an ocean area and has therefore picked up a lot of moisture
      - Polar Continental (PC)
        From the polar regions, it has travelled over land
      - Artic Maritime (AM)
        Has travelled from the arctic over the ocean picking up moisture
      - Tropical Continental (TC)
        Travels from North Africa overland picking up little moisture
      - Tropical Maritime (TM)
        Travels from the tropics but forms over the sea so produces lots of moisture
      - What does this mean for the UK?
        Polar Continental (PC)
        In winter, the air mass is cold so the airstream warms as it approaches Britain, causing it to become unstable. It brings very cold weather in winter and dry conditions in summer
        
        Polar Maritime (PM)
        Starts off cold at its base as it moves towards Britain. Brings unstable cool and showery conditions
        
        Tropical Continental (TC)
        Very stable; it brings hot and dry conditions
        
        Tropical Maritime (TM)
        Mild wet weather in winter and warm damp weather in summer
        
        Arctic Maritime (AM)
        Brings very cold temperatures and rain in winter
  - Activity Four: Describe and Explain the Origin and Nature of Anticyclones
    - Anticyclone: An area of high atmospheric pressure that is slow moving and are dominated by subsiding air
    - Weather characteristics associated with anticyclones
      - High Pressure
        Air sinking into one area, increasing the concentration of air in one area
      - Clear Skies
        Warm air leads to evaporation, humidity decreases leading to no clouds
      - Hot in Summer
        Intense insolation with a lack of clouds
      - Cold in Winter
        Heat can not be trapped due to a lack of cloud cover
      - Light Winds
      - Heat wave in Summer
        Anticyclones move slowly and block out other weather systems causing heat waves
    - Fog
      - Radiation Fog
        This occurs overnight when there are clear skies and there is radiation from the cold ground. As the ground cools, moisture in the air close to the ground and condenses forming fog
      - Advection Fog
        When warm moist sir moves horizontally over a cooler land or sea surface it is cooled from below. If the temperature of the air cools below due point, condensation occurs and advection fog is formed
  - Activity Five: Describe and Explain the Origins and Nature of Depression
    - The Formation of a Depression
      - Warm air constantly moves out of tropical areas, towards the poles. A warm front is the leading edge of a warm air mass (usually tropical maritime)
        Cold air moves out of polar regions, towards the tropics. A cold front is the leading edge of a cold air mass (usually polar maritime)
        Where the air masses meet, the warm air heading towards the poles rises above the cold air because it is more dense
        The rising warm air reduces atmospheric pressure. Strong winds blow from surrounding areas of high pressure towards this area of low pressure the whole system starts to rotate
    - The Development of a Mature Depression
      - Warm air forms a bulge into the cold air
        This is an an embryo depression
    - Weather Conditions associated with a Depression
      - Ahead of the warm front, its cool because the cold air is overhead. Thin cirrus clouds form high up
        As the warm front passes it gets warmer. Nimbostratus clouds form producing light rain over a long period of time
        When the warm sector is overhead it is warm with no cloud and relief rainfall only
        As the cold front passes, temperatures reduces and cold air undercuts the warm air. This increases the uplift rate and forms cumulonimbus clouds. Causing heavy short downfalls of raim
    - Occlusions
      - As the cold front moves faster than the warm front it eventually catches the warm front to form an occluded front.
        The warm sector is lifted completely up off the ground as it undercut by the cold front
        There is no warm air left to be uplifted so there is less rainfall. There is little condensation so cloud cover decreases. Wind speed also decreases
  - Activity Six: Discuss the Processes and Impacts related to British Storms
    - The Impact of Weather systems on the UK
      - Positive Impacts of Depressions
        Lots of rain - reliable water supply
        Irrigation/farming made easier
        Wind is used for renewable energy
      - Negative Impacts of Depressions
        Predicting weather made difficult
        High winds cause damage
        Heavy rains cause flooding
        Distribution to sporting events
      - Positive Impacts of Summer Anticyclones
        Heat waves in the south
        Good for seasonal businesses
        Boost for tourism
      - Negative Impacts of Summer Anticyclones
        Droughts
        Roots breaking up
        Heat stroke
      - Positive Impact of Winter Anticyclones
        Provides light relief
        Provides insolation for the ground
      - Negative Impact of Winter Anticyclones
        Big freeze
        Heavy snow
        Illness/injury more common
        Elderly people are vulnerable
        Affects transport (flights/trains)
        Increased insurance claims
    - Storm Formation
      - Cold polar air meets warm tropical air
        Creating the polar front and thus depressions
      - Rapid movement across the Atlantic
        Driven by the polar jet stream
      - Maritime Air
        Resulting in unstable rising air
      - Autumn storms due to warmth of ocean from summer heating
        High moisture levels creating high rainfall
      - Steep pressure gradient
        Creating very strong winds
    - The Great Storm (1987)
      - 18:00 15th Oct.
        Calm winds and wind isobars
        
        Warm front of depression, light rainfall only
        
        MET OFFICE predicted heavy rainfall in the south only
        
        Bay of Biscay (embryo depression)
      - 24:00 16th Oct.
        Heavy rainfall due to cold front
        
        Centre of depression over Cornwall
        
        Warm sector covering southern UK
        
        Strongest winds still over France
      - 06:00 16th Oct.
        Centre has now passed
        
        Very strong winds
        
        Occlusion forming
    - Impacts
      - Physical
        15 million trees blown down
        
        Broadleaf trees badly damaged
        
        Non-native trees were hard hit
        
        Orchard trees were devastated
      - Social
        18 deaths
        
        Houses and cars damaged
        
        People scared of high winds
        
        30 schools closed due to damage
        
        Fire Brigade 6000 calls in 24 hours
      - Economic
        Employed population struggled to work
        
        Power cables and pylons damaged
        
        Rail services disrupted
  - Activity Seven: Understand How Climate is Influenced by Urban Areas
    - Temperature
      - Urban Heat Island Effect
      - Air pollution increases cloud cover. Allows shortwave radiation, traps outgoing radiation
      - Rock absorbs heat during the day which is released slowly at night
      - Heat from industries, buildings, vehicles and people
      - Higher thermal heat capacity (low albedo)
      - Reduced evapotranspiration means that more energy is available to heat the atmosphere
      - Changes over Time
        Diurnal
        Daytime -0.6 higher
        
        Night-time - 3.5 higher
        
        Seasonal
        Mean winter term 2 warmer
        
        Summer mean temp 5 higher
        
        Park
        Lower temp / cooler due to light surface / more evapotranspiration
    - Precipitation
      - Air is unstable. Warmer air over urban area
      - Source of uplift. Temperatures. Tall buildings create more upward movement of air
      - A source of moisture. Individual emission increase amount of water vapour
      - High concentration of condensation nuclei
    - Wind
      - Reduction of wind spped
      - Buildings create frictional drag so average wind speeds are lower
      - Shelter on leeward sides of the buildings
      - Highest pressure on windward side of buildings
      - Turbulence occurs on leeward side
      - Bridgewater Place in Leeds caused the death of 1 man due to the venturi effect. This road is now closed when wind-speeds are predicted to be 45mph. Building will have large screens and baffle boards to deflect wind.
- The Jet Stream
  - There are four jet streams
  - Fast flowing air moving from west to east
  - One at the same latitude as the UK
- Atmospheric Heat Budget
  - 51% insolation actually reaches the earths surface
  - Rest of insolation: 16% absorbed by atmosphere/ 3% absorbed by clouds/6% reflected by atmosphere/20% reflected by clouds
- Ocean Currents
  - North - Clockwise South - Anti-clockwise
  - Warm currents flow along the east side
    - E.g. Humbolt current. Produces dry climates in western Africa
  - Cold currents flow along the west side
    - Atacama Desert. Produces a drier climate in Chile/Peru
- Structure of the Atmosphere
  - Tropopause
    - Temperatures decrease at a rate of 6.5 degrees per km because it is adiabatically cooling. Weather occurs here
  - Stratosphere
    - Planes fly here due to no weather and heat rises due to O-Zone which absorbs UV radiation
  - Mesophere
    - Drop in temperature because there is no clouds or water vapour
  - Thermosphere
    - Heat rises due to high proportion of atomic oxygen which absorbs UV radiation
- La Nino/El Nino
  - As the Earth's surface is from above, it is logical that the upper surface of the ocean is warmer than the underlying layers. The change in temperature in sudden places is called the THERMOCLINE
    - The ocean on the west side of the Pacific is warmer on the east. This means the air above the ocean is heated and rises leading to low pressure.
      - Meaning that it will be wetter on the west side of the Pacific and dry on the east
        However every two to seven years this circulation is reversed El Nino
- Effects of Latitude on Insolation
  - Insolation is highest along the tropics (lower than the equator) This is significantly lower than the poles. Strange peak of insolation in Australia
    - The sun is at an oblique angle over the poles so less insolation
    - The equator has a constant insolation because it is always equidistant from the sun
    - There is a hole in the O-Zone layer over Australia so more insolation
    - The sun is at a close angle over the tropics hence more insolation

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Weather and Climate and Associated Hazards (Part 2)

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