2024
Precipitation - II
TP2301 - Climatology
Dela Arinda, S.Si, M.Si
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Overview
This chapter will discuss precipitation part II, focusing on the types of rainfall, such as
convectional, orographic, and front rainfall, and the mechanisms behind their
formation. It will then delve into rainfall measurement instruments, including their
principles. Finally, the chapter will explore the effects of rainfall on agriculture,
highlighting both its beneficial and adverse impacts on crop growth.
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Objectives
After completing this chapter, you should be able to:
-Understand about types of rainfall
-Understand about rainfall instrument
-Understand the effect of rainfall on agriculture
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Content
1. Precipitation
2. Types of precipitation
3. Precipitation Formation
4. Types of Rainfall
5. Rainfall Instrument
6. The effect of Rainfall on Agriculture
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What is precipitation?
TP2301 - Climatology
4.Types of Rainfall
Rainfall
A. The process of B. Intensity
occurrence
• Light Rainfall
• Orographic Rainfall • Moderate Rainfall
• Convection Rainfall • Heavy Rainfall
• Frontal Rainfall • Very Heavy Rainfall
• Extreme Rainfall
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What is rainfall?
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A. The Process of Occurence
Orographic Rainfall
• Orographic rainfall produced when moist
air is lifted as it moves over a mountain
range.
• As the air rises and cools, orographic
clouds form and serve as the source of
the rainfall
Source : https://www.britannica.com/
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Convection Rainfall
• Convectional rainfall occurs when the sun’s
energy heats the surface of the Earth
• Causing water to evaporate to form water
vapour
• Convectional rainfall is widespread in areas
where the ground is heated by the hot sun, such
as the Tropics.
Source: https://www.internetgeography.net/
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Front Rainfall
• Occurs when warm air mass meets cold
air mass
• The lighter warm air rises above the cold
air, causing condensation and rain
Source: https://gpres.weebly.com/
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B. Intensity
Light Rainfall <2,5 mm/hour
Moderate Rainfall 2,5-10 mm/hour
Heavy Rainfall
10– 50 mm/hour
Very Heavy rainfall >50 mm/hour
Source: Alhassan and Ben-Edigbe 2010
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• Light rain (0,5-20 mm/day) : green
• Moderate rain (20-50 mm/day) : yellow
• Heavy rain (50-100 mm/day) : orange
• Very heavy rain (100-150 mm/day) : red
• Extreme rain (>150 mm/day) : purple
Source: bmkg
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why does light rain
last longer than heavy rain?
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What do you think caused
the flooding in Medan?
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Source: windy.com
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5. Rainfall Instrument
Rainfall Instrument
A. Manual B. Otomatic C. Remote Sensing
Ombrometer Hellman Precipitation Satellite
Gauge
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A. Manual (Ombrometer)
Source: bmkg
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The total volume of water collected is 300 ml (300 cc or 300 cm3) and
the cross-sectional area 100 cm2.
What was the amount of rainfall on that day?
TP2301 - Climatology
The total volume of water collected is 300 ml (300 cc or 300 cm3) and
the cross-sectional area is 100 cm2.
Rainfall = volume of water / the cross – sectional area
= 300 cm3 / 100 cm2
= 3 cm
= 30 mm
then the amount of rainfall on that day is 30 mm
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B. Otomatic (Hellman Precipitation Gauge)
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C.Remote Sensing (TRMM)
Satellites such as TRMM (Tropical
Rainfall Measuring Mission) use
infrared or microwave sensors to
detect rainfall from space.
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C.Remote Sensing (GPM)
• Using a vehicle (satellite)
• Has a wide range
• Can be used to estimate regional
rainfall in real time
• Able to estimate rainfall in areas that
do not have observation stations
(ungauge).
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6. The Effect of Rainfall on Agriculture
Water Supply Plant growth
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Increase nutrient
Quality and quantity of food crops
availability
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Puddles Decrease productivity
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Diseases and pests Decrease productivity
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Give an example of the effect of rainfall
on agriculture?
Question & Answer
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