Type of rainfall (Hydrology)

NAME : REG NO :

NORFARHANA AIN BINTI ZAINAL ARIFF 01DKA10F2036

ZURHAYATI BINTI MAT ESA 01DKA10F2041

NURUL HUSNA BINTI MOHAMED ROSHIDI 01DKA10F2043

SOLEHUDDIN BIN JAMAL ABD NASER 01DKA10F2045

NORSYAMIMI BINTI KHOSIDI 01DKA10F2047

SITI RASHIDAH BINTI ABD RAZI 01DKA10F0270

CC 606 : HYDROLOGY

Chapter 2 :Type Of Rainfall

Artificial

Rainfall

Introduction

• Artificial rainfall is also known as Cloud Seeding.

• Cloud seeding is a weather modification system that aims

to boost precipitation or rain by introducing condensation

nuclei such as salt or dry ice

1st Stage

The first stage is Agitation. That is using chemicals to

stimulate the air mass upwind of 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

of absorbing water vapor from the air mass , thus

stimulating the condensation process

2nd Stage

The second stage is called Building-up stage. Here the

cloud mass is built up using chemicals such as kitchen

salt, the T.1 formula, urea, ammonium nitrate, dry ice,

and occasionally also calcium chloride to increase nuclei

which also increase the density of the clouds

3rd Stage

In the third stage of bombardment chemicals 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) and makes them fall

down as raindrops. The process is called seeding

THESE RADDARS KEEP UPTO

DATE INFORMATION

OF THE WEATHER

CHANGES.

Disadvantages

[1] The Chemicals used in the production of artificial rain could affect

climatic patterns, ecosystem, water sources and the soil.

[2] Once started this process is uncontrollable.

[3] Cloud Seeding causes Flood's, Hurricane's and Thunderstorm's which

result's in loss of many lives.

Convectional

Rain(olakan)

INTRODUCTION

• Convection 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 orographic rainfall?

• 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 winds

A mosque is submerged after Cyclone Yemyin made landfall in Balochistan

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

References

• http://www.ask.com/question/what-is-frontal-rainfall

• http://www.winapedia.org/2013/04/types-of-rainfall-frontal-rain.html

• http://www.s-cool.co.uk/gcse/geography/weather-and-climate/revise-it/rainfall-types