wind and waves Flashcards
how are waves created
wind blows over the surface of the sea - friction between wind and sea forms waves - waves follow an orbital movement (tides) - when a wave reaches shallow water the wave is slowed due to friction with the sea bed - the wave spills forward moving sediment forward as swash - it then draws back to sea carrying sediment as backwash
what 3 things is wave energy controlled by
the force of the wind and its direction
the duration of the wind
the fetch - longer the fetch the more energy the wave possess
features of constructive waves
builds beaches
have a longer wavelength, lower heigh and are less frequent (6-8 per minute)
swash is greater than backwash - add material to beaches - giving slight slope to beach
features of destructive waves
have a shorter wavelength - greater height - more frequent (10 - 14 per minute)
backwash is greater than swash - sediment is dragged offshore
creates a steeper beach profile (short term) however flattens as material is dragged backwards
forms shingle ridges at back of the beach