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NAME :REG NO :NORFARHANA AIN BINTI ZAINAL ARIFF01DKA10F2036ZURHAYATI BINTI MAT ESA01DKA10F2041NURUL HUSNA BINTI MOHAMED ROSHIDI01DKA10F2043SOLEHUDDIN BIN JAMAL ABD NASER01DKA10F2045NORSYAMIMI BINTI KHOSIDI01DKA10F2047SITI RASHIDAH BINTI ABD RAZI01DKA10F0270

CC 606 : HYDROLOGY

Chapter 2 :Type Of Rainfall

Artificial Rainfall

IntroductionArtificial rainfall isalso known asCloud Seeding.

Cloud seeding is a weathermodification system that aims toboost precipitation or rain byintroducing condensation nucleisuch as salt or dry ice

1st StageThe first stage is Agitation. That is usingchemicals to stimulate the air mass upwindof the target area to rise and form rainclouds. The chemicals used during this stage are calcium chloride, calcium carbide, calcium oxide, a compound of salt and urea, or a compound of urea and ammonium nitrate. These compounds are capable ofabsorbing water vapor from the air mass , thus stimulating the condensation process

2nd StageThe second stage is called Building-up stage. Here the cloud mass is built up usingchemicals such as kitchen salt, the T.1 formula, urea, ammonium nitrate, dry ice, andoccasionally also calcium chloride to increase nuclei which also increase the density of the clouds

3rd StageIn the third stage of bombardmentchemicals such as super-cool agents: silver iodide and dry ice are used to reach the most unbalanced status which builds up large beads of water (Nuclei) andmakes them fall down as raindrops. Theprocess is called seeding

THESERADDARS KEEPUPTO DATE INFORMATIONOF THEWEATHER CHANGES.

Disadvantages[1] The Chemicals used in the production ofartificial rain could affect climatic patterns, ecosystem, water sources and the soil.

[2] Once started this process isuncontrollable.

[3] Cloud Seeding causes Flood's, Hurricane's and Thunderstorm's which result's in loss ofmany lives.

Convectional Rain(olakan)

INTRODUCTIONConvection occurs when the Earth's surface, mainly in the equatorial region, within a conditionally unstable, or moist atmosphere, becomes heated more than its surroundings, leading to significant evaporation. It falls as showers with rapidly changing intensity. Convective precipitation falls over a certain area for a relatively short time, as convective clouds have limited horizontal extent.

Orographic Rainfall

What is orographicrainfall? The word "orographic" means that it is related to mountains. Orographic rainfall is when a parcel of air containing water vapor gets to a mountain ,it is then forced upwards (the mountain blocking its way ).As the parcel of air is forced upwards, it expends (adiabatic expansion ) and also cools. As it cools ,it becomes saturated because the amount of water it can hold decreases ,so the water vapor begins to condense and finally falls as rain.

At mountainous regions, air drops down over the high ground, gaining temperature and increasing the amount of water it can hold.

That is why the flat regions below mountains hardly experience rain, and this area is known as rain shadow.

Orographic Rainfall

Orographic Effect

Frontal Rainfall

What is Frontal Rainfall?

Frontal rainfall can be defined as the rising of a warm air mass over a cool air mass. This is then followed by condensations and felling of rainfall.

Frontal rain is rain that occurs as a result of meeting the hot air mass and cold air mass.

Frontal Rainfall occurs when Two air masses meet, one a warm air mass and one a cold air mass.

The lighter, less dense, warm air is forced to rise over the denser, cold air.

This causes the warm air to cool and begin to condense.

As the warm air is forced to rise further condensation occurs and rain is formed.

Frontal rain produces a variety of clouds, which bring moderate to heavy rainfall.

Stage 1.An area of warm air meets and area of cold air.Stage 2.The warm air is forced over the cold airStage 3.Where the air meets the warm air is cooled and water vapour condenses.Stage 4.Clouds form and precipitation occurs

Cyclonic Rainfall

What is Cyclonic Rainfall???

Cyclonic or 'frontal' rain occurs where two air masses meet and form a 'front'. The warmer, moisture laden air rises over the colder air as a 'warm front'. As the air rises it cools, and its relative humidity increases. Clouds form as water vapour condenses, and then fall as rain

Where does frontal/cyclonic rain fall occur?

"Frontal/Cyclonic rain is caused by cyclonic activity and occurs along fronts.

It is formed when two air masses of different temperature, humidity and density meet such as the meeting of a tropical maritime air mass and a polar air mass.

A zone called a front separates them. At the warm front, the lighter warm air rises gently over the heavier cold air which remains close to the ground.

As the warm air rises, it expands and cools and condenses to form clouds (altostratus). The rain falls steadily for a few hours to several days.

At the cold front, the cold air forces warm air up aggressively, causing it to rise quickly and condense, forming cumulonimbus clouds.

The heavy rain that falls is of short duration. Such rain is usually associated with temperate depressions (temperate cyclones).

Cyclones form in which month?

from May till June and then from September till October

monsoon season

15 April to 15 Julyand also after its withdrawal that is 15 September to 15 December

DESTRUCTIVE ELEMENTS IN TROPICAL CYCLONES

Cyclone producing heavy rainfall and high windsA mosque is submerged after Cyclone Yemyin made landfall in Balochistan

Fully formed tropical cyclone with an eye, eyewall, and circulating rain bands

Referenceshttp://www.ask.com/question/what-is-frontal-rainfallhttp://www.winapedia.org/2013/04/types-of-rainfall-frontal-rain.htmlhttp://www.s-cool.co.uk/gcse/geography/weather-and-climate/revise-it/rainfall-types