This document discusses different types of rainfall including artificial rainfall, convective rainfall, orographic rainfall, frontal rainfall, and cyclonic rainfall. It provides details on the stages and processes involved in artificial rainfall (cloud seeding). It describes convective rainfall as occurring from heated air in equatorial regions leading to rapid showers. Orographic rainfall is explained as air forced upwards over mountains, cooling and condensing into rain. Frontal rainfall involves warm air rising over cold air at fronts, cooling and producing clouds and rain. Cyclonic rainfall occurs along fronts formed by different air masses meeting in temperate depressions.

1. 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

3. 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

4. 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

5. 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

6. 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

9. THESE RADDARS
KEEP UPTO
DATE
INFORMATION
OF
THE WEATHER
CHANGES.

10. 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.

11. Convection
al
Rain(olakan
)

12. 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.

15. • 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.

16.  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.

20. 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.

21. 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.

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

25. 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

26. 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.

27. 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).

29. 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

30. DESTRUCTIVE ELEMENTS IN TROPICAL
CYCLONES
Cyclone producing heavy rainfall and
high winds
A mosque is submerged after Cyclone
Yemyin made landfall in Balochistan

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

32. 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