TROPICAL STORM

TROPICAL STORM

Occurs in the coastal areas in the tropics

Bring heavy rainfall and strong winds speed about 200 km per hour

Accompanied by thunder and lightning

In Japan, China & the Philippines are called Typhoon

In Bangladesh and Australia is known as Tropical Cyclones

Atlantic areas they are called Hurricanes

THE FORMATION OF TROPICAL STORM


Develop over the warm oceans when the surface temperatures exceed 27◦C
When air over the sea get heated, it expands and rises very rapidly.
This create an area of intense low pressure.
Warm moist air rises to a great heights, condensing to form clouds and rain.
Air from the surrounding higher pressure area rushes inward in a spiraling manner to replace the rising warm air.
The air spin in at speed of about 200 km per hour, absorbing large amount of moisture and forming cumulonimbus clouds and heavy rains.

The cold air then sink, the centre of the storm is called the eye in area of calm weather marked by clear skies

 

THE EFFECTS OF TROPICAL STORM

Destroy life – especially in the populated areas
Destroy property- uproot trees, destroy crops and houses
Storm surges- when strong winds raise the ocean surface into a giant waves and destroy coastal settlements and flood large areas.
Flood – a covering water over land which is normally dry which are related to weather.

a) continuous rain- a longer period of rain, when the water cant seep inside the ground and more runoff

b) snow melt- snow melt and increase the volume of water in the river and runoff

c) storm surge

Droughts- unusual long period during which little or no rain falls.

CASE STUDY : BANGLADESH

Storm surges 19th April, 1990 in Bangladesh

Huge waves up to 7 m high

Destroy hundred thousand of trees

Killed 132, 000 people

Injured 458,000

Loss of large portion of their land and fish farms

Storm Surge in Bangladesh

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Precipitation

Precipitation is caused when moist air rises, water vapour in the air cools  and  condenses  to forms clouds.

Air cools upwards through the atmosphere because temperature falls with altitude because the Earth’s atmosphere is heated from the Earth’s surface up over.

When the water droplets in clouds grow to a certain size, gravity causes them to fall because of their own weight. Water droplet will fall as rainwater or precipitation.

Three main types of precipitation

1.Convectional rainfall

Convectional rainfall is more common in Brunei. It occurs in areas with hot, humid climates like equatorial regions.

This type of rain happens when the earth gets so hot that the warm air mass above it rises.

The air cools, condenses and cumulonimbus clouds form.

Heavy rainfall with thunder and lightning follows.

CONVECTIONAL RAINFALL

2.Relief rainfall

Relief rainfall occurs where the air over the sea moves over the land and is forced to rise over hills or a mountain range.

This air cools, condenses and forms clouds – the result is rain.

As the air descends the mountain on the other side, it warms and sinks.

Much less rain occurs on this side of the mountain. (Rainshadow)

RELIEF RAINFALL

3.Frontal rainfall

This rain occurs when a warm air mass meets a cool air mass.

The warm air mass is forced to rise over the cold air mass.

When the warm air rises it cools, condenses and forms rain clouds.

FRONTAL RAINFALL

CLOUD

The Formation of the cloud

Formation of Cloud

A diagram showing how the formation of cloud

TYPES OF CLOUD

Cirrus- high level cloud, composed of ice crystal than water thin, fine weather wispy, sunset

CIRRUS

Cumulus-massive rounded ,flat base,extend to great height, fair weather

CUMULUS

Stratus- low greyish,sheet layers, cover entire sky,light drizzles

STRATUS

Cirrocumulus- white round masses

CIRROCUMULUS

Cumulonimbus- are cumulus clouds, great vertical extent, heavy rain, warm morning, afternoon bring convectional rain, lightning and thunders

CUMULONIMBUS

Stratonimbus-dark rain clouds

Stratocumulus- lumpy and grayish

FORMATION OF SPITS AND TOMBOLOS

A Spit is a long, narrow ridge of deposited materials that extends from the mainland into the sea. An example in Brunei is Muara Spit and Kuala Tutong Spit.
When the spit is connected the island to the mainland to form a feature is called the Tombolos.

Spits & Tombolos

The long shore drift transports materials along the coast. If there is a sudden change in the direction of the coast, the longshore drift continues to transport the materials in the original direction to the deep sea
As the longshore drift enters the deep water, the materials are deposited. Over time, these materials accumulate above the water to form a spit.
The spit continues to grow with the continuous deposition of materials.
The spit join a nearby island to the mainland to form a tombolo.

formation of Spits

FORMATION OF OFFSHORE BAR

Off shore bar is a long narrow ridge of deposited materials sand can be found lying away from and parallel to a coast.

OFFSHORE BAR

When the waves approach a gently sloping coast , friction between the waves and the sea bed causes the waves to break at some distance from the coast.
Over time, more materials  are built up parallel to the coast to form ridge of sand called offshore bar.
A body of coastal water may be partially or completely cut off from the open sea by the offshore bar. The body of water is called a lagoon.

FORMATION OF BEACHES

Beach is a zone of materials accumulated along the coast.

DID YOU NOTICE THE HEADLAND ROCKS ARE THE SAME COLOUR WITH THE BEACH DEPOSITED MATERIALS? EXPLAIN HOW THE PROCESS WORKS?

A beach is formed when deposited materials carried by waves are accumulated in a zone along the coast. The materials on the beach vary in size from fine sand to pebbles . The waves sort these materials according to the weight. The finer sand deposited nearer the sea and the coarser materials further inland.

DEFINITION

DEFINITION OF COASTAL EROSIONAL FEATURES

CLIFF-is a steep rock face.
WAVE CUT PLATFORM-A gently sloping rock surface which extends towards the sea from the foot of the cliff.
HEADLAND– A  steep rock face which projects into the seas.
BAYS– a wide curves of land along the coast which encloses part of the sea.
CAVES– is a hollow with an opening in  a mass of rock.
ARCH– is a bridge of rock above an opening.
STACK– is a pillar of rock left behind after an arch collapses.