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Hydrology
Introduction for Hydrology
Module 1 (Part 1)
Geophysics and Meteorology
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Reason why we have HYDROLOGY…?
The reason is …?
The SUN
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Solar Radiation
Meteorology Today: An
Introduction to Weather, Climate, and the Environment (Donald Ahrens, 2004)
Solar Radiation
https://energiasalternativasiutc.blogspot.com/
The sun is
the driver of
hydrology
on Earth
solar constant = 1,374 W/m2
rate of solar radiation reaching the
upper limits of earth atmosphere on a
surface normal to the incident radiation
at earth’s mean distance from the sun
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Solar Energy
Budget Solar
Energy Budget
https://ag.tennessee.edu/solar/Pages
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Albedo
sci.uidaho.edu
fraction of
the
incoming
solar radiation that is
reflected from a surface
Sun
Protection Factor or SPF
It is a measure of how well a sunscreen will protect skin
from UVB rays, the kind of radiation that causes sunburn,
damages skin, and can contribute to skin cancer.
If your skin would normally burn after 10 minutes in the
sun, applying an SPF 15 sunscreen would allow you to
stay in the sun without burning for approximately 150
minutes (a factor of 15 times longer).
This is a rough estimate that depends
on skin type, intensity of sunlight and
amount of sunscreen used.
SPF is actually a measure of protection from
amount of UVB exposure and it is not meant
to help you determine duration of exposure.
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Sun Protection Factor or SPF
https://www.badgerbalm.com/s-30-what-is-spf-sunscreen-sun-protection-factor.aspx
Then for SPF 50 - blocks 98% of UVB rays
Example
An athlete with an exposed body area of 0.25 m2just
applied a sunblock with SPF 30. If the solar constant is
1,374 W/m2 and 50% of that reaches the athlete’s skin
based on common solar energy budget:
How much solar energy in Watt-hour has been absorbed
by the body if the exposure to sun lasted for 5 hours?
How much solar energy in Watt-hour has been absorbed
by the body if the exposure to sun lasted for 7 hours?
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Example
How much solar energy in Watt-hour has been absorbed
by the body if the exposure to sun lasted for 5 hours?
������������ = ������ = 1374��/��2 0.25��2 1 − 0.93 5ℎ���� =
120.225 ��ℎ��
How much solar energy in Watt-hour has been absorbed
by the body if the exposure to sun lasted for 7 hours?
������������ = ������ = 1374��/��2 0.25��2 1 −
0.93 5ℎ���� +
1374��/��2 0.25��2 1 2ℎ���� = 807.225 ��ℎ��
Because after 5 hours the sunblock
no longer blocks the radiation,
that’s why the last 2 hours the fraction is 1 as used.
Sun and Earth Geometry
Samantha Lee/Business Insider
APHELION: sun is farthest from the earth
(occurs about July 4) about 152 million km.
Distance between Sun and Earth affects
PERIHELION: sun is nearest from the earth
the solar radiation received at any
(occurs about January 3) about 147 million km.
location and time.
https://looking-at-the-universe.tumblr.com
Animation:
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Sun and Earth Geometry
https://www.businessinsider.com
Equinox: sun passes directly over the equator or when the sun’s apparent path and plane of the earth’s
equator coincide
Inclined Earth
Solstice: when the sun’s apparent path is displaced farthest north or south from the earth’s equator
https://en.wikipedia.org/wiki/Orbit_of_the_Moon
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Seasons
https://mrstatesolarsystem.weebly.com/our-perspective-fro
means winter
m-earth.html
hemisphere
in southern
and vice versa
seasons occur due to tilting of
earth’s axis.
summer in northern hemisphere
Global Circulation: WITHOUT the Earth’s rotation
From equator, air
moves upward then
towards the pole
(upper atmosphere).
From the poles, air
moves downward then
towards the equator
(lower atmosphere).
https://www.theweatherclub.org.uk
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Global Circulation: WITH the Earth’s rotation
1. latitudinal difference in heating
of the earth’s surface
2. inclination of the earth’s axis of
rotation
3. mechanics of the fluid flow
4. Coriolis effect: rotation of earth
https://www.theweatherclub.org.uk
Three-Cell Global Circulation
The overall effect of the solar
energy received by the Earth is the
circulation of air on a global scale.
https://content.meteoblue.com/es/meteoscool/el-clima-a-gran-escala-lsw/atmospheric-circulation
Circulation
Local
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Local
Circulation
General Movement:
from High pressure to
Low pressure area
General Movement:
from warmer place to
colder place
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Land and Sea Breeze
Land breeze is a wind blowing
from land out towards a body of water.
Sea breeze is a wind blowing from the
water onto the land.
Land breezes and sea breezes arise
because of differential heating
between land and water surfaces.
Geography and Wind
• Rainshadow
Effect
• Orographic
Nature
https://blog.weatherops.com/do-you-know-how-upslope-flow-affects-the-weather
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Geography and Wind
Weather and Climate
Weather:
daily condition of
the atmosphere.
Climate: Long-term average (over
decades) of weather conditions: mean
annual temperature, mean total
precipitation, etc.
https://www.cbc.ca/kidscbc2/the-feed/whats-the-difference-between-weather-and-climate
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Pressure
Barometer for atmospheric pressure
https://www.quora.com/What-causes-helium-weather-balloons-to-expand-as-they-rise
Temperature
https://aviation.stackexchange.com/questions/
Altitude in kilometers
Temperature
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Temperature
http://blogdesocialesabraham.blogspot.com/2017/01/the-atmosphere-and-its-changes.html
Humidity
amount
of water
vapor
found in
the air
https://www.oceannews.com/featured-stories/
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Relative Humidity
Wind
amount (in %) of water vapor that is present in the air
at a
given time compared to the maximum percentage
of water vapor the air is capable of holding
Anemometer:
measures wind speed
https://www.businessinsider.com/cool-earth-wind-map-2014-2
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Philippine Climate
Climate Controls in the Philippines
• Topography and location
• Trade winds
• Fronts
• Intertropical convergence zone
(ITCZ) • Monsoon winds
• Tropical cyclones
• Easterly waves
Coronas, Jose (1920). The Climate and
Weather of the Philippines, 1903 – 1918.
Manila Observatory: Bureau of Philippines.
Climate
The Corona Classification
Type 1
Type 2 Type 3 Type 4
TYPE 1. Two pronounced wet
and dry seasons: wet during
the months of June to
November and dry from
December to May.
TYPE 2.
No dry season
with
a
very
pronounced maximum rain
period in December, January
and February.
TYPE 3. No pronounced
maximum rain period and short
dry season lasting from one to
three months.
rainfall.
TYPE 4. Uniformly distributed
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Inter-tropical Convergence Zone (ITCZ)
https://expeditionusf.wordpress.com/
Tropical Cyclones
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Typhoon Structure
Monsoons
Monsoon: seasonal
reversing wind with
corresponding changes in
precipitation and
atmospheric circulation
In the Philippines
Northeast Monsoon
(Amihan: Oct to Mar)
Southwest Monsoon
(Habagat: May to
Sept)
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Easterly Waves
Elongated area of
relatively low
pressure region
Region of isobars
pressure lines)
that seems pressed
or gripped.
(equal
References
V.T. Chow, D.R. Maidment, and L.W. Mays (1988):
Applied Hydrology, McGraw-Hill Education New York
P.J.M. de Laat and H.H.G. Savenije (2002):
Hydrology – Lecture Notes, Delft, Netherlands
C.D. Ahrens and R. Henson (2009): Meteorology Today:
An Introduction to Weather, Climate and the Environment
– 9th Edition, Brooks/Cole Publishing, London
Chong-yu Xu (2002): Textbook of Hydrologic
Models, Uppsala University, Sweden
V.T. Chow (1959): Open Channel Hydraulics, University
of Illinois, McGraw-Hill Book Company, New York
USDA - NRCS (1986): Urban Hydrology for Small Watersheds
TR-55, USDA Natural Resources Conservation Service
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