Geography test 2

WAVES ARE THE MOVEMENT OF ENERGY THROUGH WATER

WAVE FREQUENCY- number of wave crests passing point A each second.

WAVE PERIOD- the time required for the wave crest at point A to reach point B.

what happens to a wave as it approachess the shore?

The first wave would go in a strong circular motion and gradually get slower. When the wave first feels the sea bed, the frictional drag slows the base of the wave (reduces wave length). The once circular wave has now turned into an elliptica shape, because the lower part of the wave makes the wave to slow down, and become faster outside in the air. This repeats until the top of the wave breaks over, causeing the wave to crash on the water. (There is no force leading the wave so it lacks momentum causing the wave to crash.)  

-The strength of the wind

-the duration of the wind

-the direction of the wind

-the fetch (the length of uninterpreted water over which a wave can be generated

CONSTRUCTIVE WAVES-

-They are low wave frequency

-Low energy

-strong swash carries materials ashore

-forms a wide, gentle, sloping beach

DESTRUCTIVE WAVES- 

-High wave frequency

-high energy

-Weak swash brings ashore little material

-Strong backwash, removes beach material, forms a steep beach scouring out the area in front

HYDRAULIC ACTION - when destructive waves breakagainst the cliffs by their sheer weight and power. the frequency and energy must be high to carry out the best erosion. They trap air in cracks in the rock which builds up pressure. The air is compressed by the wave, eventually after the pressure has built up, it will cause the rock to break apart (cavitation)

CORRASION (ABRASION)  - Particles (sand) or large stones which are sharp and hard are carried by the waves. These waves crash against the cliff and slowly erode the edge of the cliffs.

ATTRITION  - Particles like sand are carried by the waves crashing against each other. The high energy of the wave also helps larger, sharper and harder rocks get carried and crash against each other. These crashes form smaller rocks, which are smoother and rounder particles. 

SOLUTION (CORROSION) - The acids in sea water slowly dissolve the chalk (carbon dioxide) and limestone. the acid dissolves the cliff. This forms calcium carbonate.

-Fetch -Strength of the waves (wind speed) -Beach -Geology of rock: average annual rate of erosion of the unconsolidated, soft, boulder clay rocks of the North Norfolk coast is 5m per year. In contrast the hard granite rocks of the SW England erode at 0.001m per year. -Joints/bedding planes -Headlands – waves converge on a headland gaining height and erosive energy

The disintegration of rocks. Where this happens piles of rock fragments caused scree can be found at the foot of cliffs.

Mechanical (Physical) Weathering - is the process of breaking big rocks into little ones. This process usually happens near the surface of the planet. Temperature also affects the land. The cool nights and hot days always cause things to expand and contract. That movement can cause rocks to crack and break apart.

Rainwater, which is slightly acidic, very slowly dissolves certain types of rocks and minerals.

Chemical Weathering- the erosion or disintegration of rocks, building materials, etc., caused by chemical reactions (chiefly with water and substances dissolved in it) rather than by mechanical processes.

Flora and fauna cause this type of weathering. For example plant roots grow in cracks in the rocks.

Biological Weathering- is the weakening and subsequent disintegration of rock by plants, animals and microbes. Growing plant roots can exert stress or pressure on rock. Although the process is physical, the pressure is exerted by a biological process (i.e., growing roots).

•Crest: The top of the wave.

•Trough: The low area in between two waves.

•Wavelength: The distance between two crests or two troughs.

•Wave height: The distance between the crest and the trough.

•Wave Frequency: The number of waves per minute.

•Velocity: The speed that a wave is traveling. It is influenced by the wind, fetch and depth of water.

•Swash: The movement of water and load up the beach.

•Backwash: The movement of water and load back down the beach.

Sand spits are long, norrow ridges of sand or shingle. one end is attached to the land, and the other end extends out into open water.

The formation of a sand spit is largely due to LONG SHORE DRIFT.

They are a dynamic land form that depends on the inter-relationship between sand and vegetation.

Conditions which allow coastal dunes to develop are:

-Small sediments, an ample supply

-Ample wind energy to pick up and move sand particles

-large tidal range 

Embryo dunes

• fresh and accumulating
• 80% bare sand
• very little humus content
• a little salt water
• very few plants
• rarely any animals maybe snails

Mobile dunes which are made up of either foredunes or yellow dunes (steeper)

Foredunes and yellow dunes both have - 20% bare sand and little but accumulating humus content.

foredunes                                                                        yellow dunes

• low amount of water                                               -Sand sedge and creeping fescue
• maram grass                                                           -Rabbits and mice 
• rabbits and mice

Fixed/ Grey dunes

• below 10% bare sand
• more humus making it look grey
• fresh water content slightly higher. Held by humus
• bambles, gorse and buckthorn
• Grazing animals 

Hollow in dunes

(Dune slack)

• high humus, brackish water in slacks
• heather, gorse on dunesjuncus in stacks

• High temperatures
• Large destructive waves bacause of large fetch
• theme parks
• tropical climate (82 degrees farenheit in March)
• Tourism is the largest sector of employment in florida -479,000 germans visited in 2016
• sandy beaches
• 176,000 jobs in the port of miami and an annual ecomic impact in miami of $18 biliion
• Florida keys are coral islands
• Flat land (10 intenationa airports)

Conservation

• Everglades is an inland wetland area
• Flordia Keys - an archipelago of 1500 islands (coral)

Population

• Average of 40 years
• increased from 9.7 in 1980 to 19 million in 2007 (many retires atracted by cooler summers. 17.5% are over 65)

HURRICAINS - conditions

• warm water (26.5+)
• in summer and autumn
• a latitude greater than 5N and 5S, any closer and there is not sufficient 'spin' resulting from the rotation of the earth
• in tropical regions of severe air instability where air is converging on the surface and rising rapidly

THE EYE IS THE SAFEST PLACE - CALM WEATHER WITH VIRTUALLY NO WIND OR RAIN

•  Air passing over a warm ocean and a huge quantity of water evaporated quickly

• This warm moist air rises rapidly creating an area of low pressure. this air cools to a DEW POINT, where condensation occurs releasing LATENT HEAT energy which causes the air to rise forming COMULONIMOUS clouds which bring torrential and thunder storms.

• Upper levelminds DIVERGE and the cooler air starts to sink at the edge of the storm

• sinking cold air creates high pressure.

• The air is pulled in from HIGH PRESSURE at the edge of the storm to LOW PRESSURE towards the centre of the storm.

• In the centre of the strom SOME cooler denser air sinks creating the eye with light winds and rain

• The storm rotates due to the rotation of the earth and the CORIOLIS FORCE.

this is developed by low pressure near the eye of the storm which pulls water higher, the winds pile up the water and push it towards the shore. The shallow coast line slope produces a greater surge than a steeper slope, waves push the water inland faster than it can drain off creating floods.