Theme 2

• Anticyclone


  A high pressure weather system. Average sea level pressure at the centre of the system is usually above 1000 millibars.
• Arch


  A natural breach or hole formed by wave erosion on each side of a headland. Two caves usually meet to form the arch.
• Attrition


  The wearing away of rock fragments as they rub against each other during transportation.
• Backwash


  The movement of water back to the sea after a wave has broken on the shore. The movement is at right angles to the coast.
• Beaufort Scale


  A scale of wind speed ranging from D (Calm) to 12 (Hurricane). A figure of 12 is over 117mph.
• Cave


  An opening within a rock. Caves form in headlands where weaker bands of rock are eroded by wave action.
• Corrosion


  The eroding away of rock surfaces by other (Abrasion) pieces of rock being carried by rivers or by the sea.
• Climate


  The average weather conditions over a long period - at least 30 years. Temperature and precipitation are the most often used climate data and are shown on climate graphs.
• Cold front


  The boundary where a cold air mass meets and pushes into a warm air mass. This is usually found in the mid-latitudes of the northern hemisphere as part of a depression.
• Deposition


  The laying down of material such as mud or sand on the sea floor and river beds.
• Distributaries


  The many channels that a stream or river splits into when it meets a lake or sea and forms a delta.
• Delta


  A landform, often triangular in shape, that develops where a river meets a slow-moving body of water such as a lake or ocean. Deposition of sediment eventually builds up above the water level forcing the river to split into distributaries to form a delta.
• Depression


  A low-pressure weather system often found in the mid-latitudes of the northern hemisphere where a warm tropical air mass pushes into a cold arctic air mass. Warm air rises to give low pressure at the centre of the weather system. This is usually less than 1000 millibars.
• Estuary


  The broad seaward side of a river mouth where there is a mix of fresh water and seawater.
• Flood plain


  A flat area of land on both sides of a river made up of sediment deposited when the river floods.
• Groyne


  A low barrier of concrete or wood built out into the sea from the coast. By trapping sand it slows down the movement of longshore drift.
• Hydrograph


  A graph which shows the pattern of a river's discharge. It is measured in m³/second (cumecs) over a period of time.
• Hydrosphere


  This is made up of all the stores and flows of water in gas, liquid or solid state e.g. clouds, rivers, ice.
• Hydraulic action


  The trapping of air under pressure by water in rivers or the sea. The energy release is explosive and helps erode the rock.
• Impermeable


  These rocks do not allow water to pass through. They are watertight e.g. clay.
• Input


  That which is put in or taken into a system. In the hydrological cycle, precipitation is an input to the drainage basin.
• Irrigation


  The artificial supply of water to land by such means as channels, sprinklers, hosepipes
• Leaching


  A chemical reaction which results in nutrients in the soil being replaced by hydrogen from rainfall. Nutrients are lost from the soil or moved deeper down the soil profile.
• Levée


  The raised banks of a river usually found in the lower course. They may be formed naturally by regular flooding or be built up by people to protect the area against flooding
• Longshore drift


  The zigzag movement of sediment along a shore caused by waves going up the beach at an oblique angle (wash) and returning at right angles (backwash).
• Maritime


  Areas close to or on the coast have their climate influenced by the sea. Due to differential heating, the sea is cooler than the land in summer and warmer in winter. Consequently maritime climates do not have such large annual temperature ranges as are found in continental climates.
• Maximum temperature


  The highest temperature recorded during a time period. This is usually during a 24-hour period but can be monthly or yearly
• Minimum temperature


  The lowest temperature recorded during a time period. This is usually during a 24-hour period but can be monthly or yearly.
• Monsoon


  Wet season
• Permeable


  These rocks allow water to pass through them e.g. chalk, limestone.
• Porous


  These rocks contain many small air spaces e.g. chalk. Most porous rocks are permeable.
• Precipitation


  Moisture that falls out of the sky (rain, sleet, snow and hail).
• Prevailing wind


  The direction from which the wind blows into an area for most of the year.
• Saltation


  A transportation method in which material "leap-frogs" over each other. Occurs as material is light enough to be picked up, but too heavy to be continually carried so is instantly dropped by the river.
• Solution (or Corrosion)


  The dissolving of rock material in water. Is also the name for a form of transportation in which sediment is completely dissolved and invisible!
• Spit


  A sand ridge that is joined to the coast at one end and juts out into the sea usually with a curve at the other end.
• Stack


  An isolated pillar of rock separated from a headland. Stacks are usually formed by the collapse of an arch.
• Suspension


  The carrying of fine (small) material near the top of a river. Evident by a brown discolouration in the river.
• Swash


  The advance of sea water up a beach after the breaking of a wave.
• Temperate


  Areas in the northern and southern hemispheres which do not experience great extremes of heat or cold. They are in the mid-latitudes between the hot tropics and cold Polar Regions.