Wind and waves influencing coasts Flashcards
(22 cards)
What are the main physical factors influencing coastal landscape systems?
Wind and waves
How is wind generated in the atmosphere?
When cool high pressure air masses move into warm low pressure air masses
What factors determine wind speed and direction?
Temperature and pressure differences, the Coriolis Effect, and friction with Earth’s surface
What happens at 0 degrees latitude in global atmospheric circulation?
Warm, humid air rises with constant warm temperatures
What occurs at 30 degrees latitude in global atmospheric circulation?
Cool, dry air descends with constant warm temperatures and bigger diurnal changes
What is the condition of air at 60 degrees latitude?
Cooler, humid air rises with seasonal temperature variability
What occurs at 90 degrees latitude in global atmospheric circulation?
Cold, dry air descends with seasonal temperatures having extreme variation
What are the direct influences of aeolian processes?
Erosion, transportation, and deposition of loose, fine-grained materials
What landforms can be influenced by wind deposition?
Spits, bars, and sand dunes
How are ocean waves generated?
By the frictional drag of wind over the surface of the water
What factors affect wave energy and size?
- Wind strength
- Wind duration
- Water depth
- Fetch of the wave
What is the circular motion of energy in a wave responsible for?
Creating peaks and troughs on the water surface
Define wavelength in the context of waves.
The distance between two successive crests or troughs
What is wave frequency?
The number of waves per minute
What is wave height or amplitude?
The distance between the trough and the crest
What happens to objects in deep water when waves pass?
They move up and down with very little horizontal movement
What occurs when a wave base intersects the sea floor?
The wave shoals/breaks and becomes a translatory wave
What is the formula to approximate the energy in a wave in deep water?
P = H2 T
What do the variables in the wave energy formula represent?
- P: power in kilowatts per metre of wave front
- H: wave height in metres
- T: time interval between wave crests in seconds
What types of wave breaking exist?
Spilling (constructive) and plunging (destructive) waves
What characterizes constructive waves?
Stronger swash than backwash, associated with shallower beach gradients and small sediment size
What characterizes destructive waves?
Stronger backwash that removes sediment, creating a steeper gradient and coarser sediment
