4.1 Causes of Waves and Tides

Flashcards covering the formation of waves, the concept of fetch, and the dynamics of uprush and backwash on the shoreline.

What is the primary cause of waves?

Waves are caused by the wind dragging on the surface of the water.

What is the definition of the fetch?

The fetch is the length of water the wind blows over.

Which three factors determine how large and energetic a wave will be?

The strength of the wind, the duration for which it blows, and the length of the fetch.

From which direction does the prevailing wind in the UK blow?

The prevailing wind in the UK blows in from the south west.

What height can waves reach out at sea during a gale?

They can reach over $30\,m$ high.

What is the term for the turbulent water created when waves break at the shore?

Swash.

What is the name for the water that rushes up the sand at the beach?

The uprush.

What is the name for the water that rolls back into the sea?

The backwash.

Under what condition do waves 'eat at the land' by dragging pebbles and sand away?

This happens when the backwash has more energy than the uprush, typically with high steep waves.

Under what condition is material carried onto the land to build a beach?

This happens when the uprush has more energy than the backwash, typically with low flat waves.