2.1.2 Sources of energy in the coast

Question 1

What are the main sources of energy in the coast?

Answer 1

• Wind
• Waves
• Tides
• Currents

Question 2

Crest

Answer 2

The top of the wave.

Question 3

Velocity

Answer 3

The speed that a wave is travelling. It is influenced by the wind, fetch and depth of water.

Question 4

Backwash

Answer 4

The movement of water and load back down the beach.

Question 5

Swash

Answer 5

The movement of water and load up the beach.

Question 6

Wave length

Answer 6

The distance between two crests or two troughs.

Question 7

Trough

Answer 7

The low area in between two waves.

Question 8

Wave height

Answer 8

The distance between the crest and the trough of a wave.

Question 9

Wave frequency

Answer 9

The number of waves per minute.

Question 10

Impact of winds on the coast

Answer 10

Winds are created by air moving from areas of high pressure to areas of low pressure. During events such as storms, the difference between high and low pressure is high, causing winds to be strong.

Strong winds can generate powerful waves. In some areas, wind consistently blows from the same direction (this is called a prevailing wind) – this causes higher-energy waves than winds that change direction frequently.

Question 11

How are waves created?

Answer 11

By wind blowing over the surface of the sea. The friction between the wind nad the surface of the sea gives the water a circular motion.

Question 12

The effect of a wave on the shore

Answer 12

The effect of a wave on the shore depends on its height. Wave height is affected by the wind speed and the fetch of the wave. The fetch is the maximum distance of sea the wind has blown over in creating the waves. A high wind speed and a long fetch creates higher and more powerful waves.

As waves approach the shore they break. Friction with the sea bed slows the bottom of the wave and makes their motion more elliptical (squashed and oval-shaped). The crest of the wave rises up and then collapses.

Question 13

Constructive waves

Answer 13

Constructive waves have a low frequency. They are low and long, which gives them an elliptical cross profile. The powerful swash carries material up the beach and deposits it. up the beach

Question 14

Destructive waves

Answer 14

Destructive waves are high and steep, with a more circular cross profile. They have a higher frequency. Their strong backwash removes material from the beach.

Question 15

Difference between constructive and destructive waves

Answer 15

Question 16

Tides

Answer 16

The periodic rise and fall of the ocean surface, caused by the gravitational pull of the Moon and the Sun.

Question 17

How do tides affect the coast?

Answer 17

Tides affect the position at which waves break on the beach. For example, at high tide they break higher up the shore. The area of land between maximum high tide and minimum low tide is where most landforms are created and destroyed.

Question 18

Neap tide

Answer 18

Moderate tides between high/low tides. The sun and the moon pull at right angles cancel each other out.

Question 19

Spring tide

Answer 19

Extreme tides – the very highest and the very lowest tides.

Question 20

Water current

Answer 20

The eneral flow of water in one direction – it can be caused by wind or by variations in water temperature and salinity.

Currents move material along the coast.