Geography paper 1

• What conditions are needed for a tropical storm to form?

  low latitude between 5-30 degrees north and south of the equator, ocean temperatures above 27 degrees, ocean depth of 70 m, between summer and autumn
• How do tropical storms form? (pt 1)

  1. Start 5-30 degrees n/s of the equator with ocean temps exceeding 27 degrees
  2. Air is heated above the surface, this then rapidly rises under low-pressure conditions
  3. The rising air draws up water and moisture from ocean causing strong winds
  4. The Coriolis affect causes the air to spin upwards around a calm central eye of the storm
• How do tropical storms form ? (pt 2)

  5. As the air rises, it cools and condenses to form large clouds which generate torrential rainfall. Heat is given off when the air cools and powers the tropical storm

  6. Cool air sinks into the eye, therefore there is no cloud so it is drier, clear and much calmer

  7. Tropical storm travels across the ocean by prevailing winds

  8. When the tropical storm meets the land, it is no longer fuelled by the moisture and heat from the ocean, so it looses power and weakens
• Monitoring and prediction for tropical storms

  • satellite and radar technology are used to track development and approach, these combined with charts and computer software are used to predict the path of a storm
• Protection for tropical storms

  The most reliable is cyclone shelters as they can withstand the hurricane because:

  • have windows covered with metal shelters
  • built off the ground with deep-pile concrete pillars that dissipate energy
  • are made from reinforced concrete
  • High sea walls are often constructed to protect communities from storm surges
• Planning for tropical storms

  • people are advised to stock up on food as they may be housebound
  • governments and NGO's educate and advise people
  • early warning systems are installed
• What is differential heating?

  when the suns rays do not heat the earth equally due to the curvature of the earth. Energy is more concentrated at the equator
• What happens at the equator (global atmospheric circulation)

  Due to high temperatures, air rises. This creates low pressure. This air then cools and condenses forming clouds that lead to rainfall.
• Why are deserts found 30 degrees n/s of the equator?

  some of the air travels 30 d n/s of the equator, this then cools and sinks. As it sinks it creates bands of high pressure. As moisture in the sinking air fell at the equator it is dry so few clouds form here. This is under the Hadley cell.
• Explain how a waterfall is formed (pt 1)

  1. water runs over alternating bands of hard and soft rock
  2. erosion will start to break down the rocks though the processes of hydraulic action, abrasion and solution
  3. Hydraulic action wears away the soft rock as the water runs over it, this is because it is less resistant than the hard rock above it
  4. overtime the soft rock starts to undercut the hard rock
• Explain how a waterfall is formed (pt2)

  5. The hard rock is left unsupported and as a result of this it's weight collapses into the riverbed

  6. Rocks have fallen are either transported downstream or scrape away at the base of the river bed through the process of abrasion, this with continuous friction from the water causes a dent in the riverbed to form. This is known as the plunge pool.

  7. The erosional processes repeat and overtime the waterfall retreats backwards

  8. Once this occurs a steep-sided gorge is left behind
• When does a riffle form?

  coarse sediment (boulders) is deposited in shallow water
• When does a pool form?

  There are areas of deep water and therefore greater erosion
• Meanders

  Found in the middle course of a river
• Formation of pools and riffles in a straight river channel

  1. Water moves around obstructions like large boulders

  2. Results in areas of slower and faster water movement
• Helicoidal flow

  River flows from side to side in a winding course
• Helicoidal flow

  1. Moves material from the outside of one meander bend

  2. Deposits it on the inside of the next bend
• Velocity is higher on the outside bend

  Erosion occurs forming a river cliff
• Deposition occurs in the inside bend

  Forming a slip off slope
• causes of river flooding

  1. relief
  2. deforestation
  3. rainfall
  4. urbanisation
  5. rock type (permeable or impermeable)
  6. soil saturation
• hydrograph

  What happens if there is a short lag time? = more likely to flood (flashy)

  What happens if there is a long lag time?= less likely to flood

  A) peak rainfall

  B) peak discharge

  C) falling limb

  D) rising limb

  E) lag time

  
• Hard engineering strategies for managing floods?

  1. Dam
  2. channel straightening
  3. embankment
  4. flood relief channel
• soft engineering for managing floods?

  1. afforestation
  2. wetlands
  3. flood plain zoning
  4. river restoration
• How do waves form ?

  As the wind blows over the surface of the sea, it creates friction which forms waves. The wind transfers it's energy causing the water to move in a circular motion.
• what is fetch and how does it affect the wave?

  Fetch is the distance it travels over the sea. The greater the fetch the larger the waves.
• what effects the size of a wave?

  1. duration the wind has been blowing for
  2. the fetch
  3. power/strength of the wind
• what are the 4 types of mass movement?

  1. rockfall
  2. landslide
  3. mudflow
  4. rotational slip
• How do wavecut platforms and notches form?

  1. sea attacks base of cliff though abrasion and hydraulic action, this causes the cracks in the base of the cliff to expand
  2. this creates a wave cut notch which becomes larger and larger
  3. erosion continues and the weight of the cliff becomes unstable and collapses leading to the retreat of a cliff face
  4. backwash carries away eroded material leaving a wavecut platform
• Hard engineering for coasts?

  1. sea walls
  2. Gabions
  3. groyne
  4. rock armour
• soft engineering for coasts?

  1. dune fencing
  2. dune regeneration
  3. beach nourishment
• How do sand dunes form?

  1. wind blows sand inland
  2. this sand builds up around obstacles like a rock to form embryo dunes
  3. dunes develop and are stabilised by vegetation (marram grass) to form fore dunes and tall yellow dunes
  4. Decomposing vegetation makes sand more fertile and a wider range of plants colonise the back dunes
  5. ponds can form in depressions
• How is a spit formed?

  1. longshore drift carries sediment along the beach
  2. there is a change in the shape of the coastline
  3. the sediment continues moving and eventually deposits out in the sea
  4. the spit is exposed to changes in the wind and wave direction which causes the end to curve and form a hook
  5. a salt marsh forms in the sheltered water behind the spit as mud deposits build up
• How is a meander and ox-bow lake formed?

  • River is fastest on the outside bend so it has more energy so lateral erosion occurs here creating a river cliff
  • River is slower on the inside bend so it has less energy so deposition occurs here forming a slip off slope
  • this meaner gets wider and the neck gets narrower until the neck eventually meets and cuts of the loop
• interlocking spurs

  erosion occurs vertically in the upper course creating a v shaped valley. It winds around areas of resistant rock to create interlocking spurs which jut out into the valley