Nces Solar
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Transcript of Nces Solar
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N.C.E.S
SOLAR RADIATION
GEOMETRY
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A PRESENTATION ON
SOLAR RADIATION GEOMETRY
By
NAME ROLL NO.
ANKUR BAROT 862
JASMINE PARKHIYA 863
NIKUNJ PARKHIYA 864
MANDAR GHANEKAR 865
MADHURI PATEL 866
DEPARTMENT OF MECHANICAL ENGINEERING
RAJIV GANDHI INSTITUTE OF TECHNOLOGY, ANDHERI (W)
MUMBAI UNIVERSITY
(2012-2013)
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CELESTIAL SPHERE An imaginary sphere with
Earth at its center. The
stars, planets, Sun, Moon,
and other celestial bodies
appear to be located on thissphere, and the sphere
appears to rotate around
the Earth's extended axis
once every 24 hours,carrying the celestial bodieswith it overhead and giving
them their motions.
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ZENITH AND NADIR Zenith is a point on the
Celestial sphere directly
over the observers head.
The Zenith would change
w.r.t. location.
Nadir is a point on the
Celestial Sphere
diametrically opposite to
the Zenith and it also
changes w.r.t. location.
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VISIBLE HORIZON The horizon (or skyline) is
the apparent line thatseparates earth from sky,
the line that divides allvisible directions into twocategories: those thatintersect the Earth'ssurface, and those that donot. At many locations, the
true horizon is obscured bytrees, buildings,mountains, etc., and theresulting intersection ofearth and sky is called thevisible horizon
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ASTRONOMICAL HORIZON
As the visible horizon is
uneven, one can not define
location in the sky with
reference to it. Therefore it
is necessary to define ahorizon, the same distance
away from Zenity (line
joining the Zenith to the
centre of earth, simply avertical line). It is an evencircle which may be either
below or above the horizon
this is called Astronomical
Horizon.
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MERIDIAN
An imaginary great circle
passing through a point
and true poles intersecting
the equator at right angles
is called the PrimeMeridian. Similar grid
circles have been drawn at
intervals of 15 degree
through the two poles.
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LATITUDE An imaginary great circle passingthrough a point and true polesintersecting the equator at rightangles is called the PrimeMeridian. Similar grid circles havebeen drawn at intervals of 15degree through the two poles.
The latitude of a pointP
on thesurface is defined as the anglethat a straight line, passingthrough both P and C , subtendswith respect to the equatorialplane.
IfP is above the reference plane,the latitude is positive and if it is
below the latitude is negative. Latitude angles can range up to
+90 degrees (or 90 degrees north),and down to -90 degrees (or 90degrees south).
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LONGITUDE Longitude is defined in terms of
meridians, which are half-circlesrunning from pole to pole.
A reference meridian, called the primemeridian , is selected, and this formsthe reference by which longitudes aredefined.
The longitude of a point Pon thesurface is defined as the angle that theplane containing the meridian passingthrough P subtends with respect to theplane containing the prime meridian.
IfP is to the east of the prime meridian,the longitude is positive; ifP is to thewest of the prime meridian, thelongitude is negative.
Longitude angles can range up to +180degrees (180 degrees east), and down to-180 degrees (180 degrees west).
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DECLINATION It is the angular distance of
the suns rays north (orsouth) of the equator.
It is the angle between aline extending from thecentre of the sun to thecentre of the earth and theprojection of this line uponthe earths equatorialplane.
This is the directconsequences of the tilt andit would vary between 23.5on June 22 to 23.5 on
December 22.
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ZENITH ANGLE It is complimentary angle of
suns altitude angle.
It is vertical angle betweenthe suns rays and a line
perpendicular to thehorizontal plane through
the point i.e. the angle
between the beam from the
sun and the vertical.
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SOLAR AZIMUTH ANGLE It is the solar angle in
degrees along the horizon
east or west of north or it is
horizontal angle measured
from north to the horizontalprojection of the suns rays.
This angle is positive when
measured west wise.
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SURFACE AZIMUTH ANGLE It is the angle of deviation
of the normal to the surface
from the local meridian.
The zero point being south
east positive and westnegative.
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ANGLE OF INCIDENCE It is the angle being
measured between the
beam rays and normal to
the plane.
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HOUR ANGLE
It is the angle through which the earth
must turn to bring the meridian of a point
directly in line with the suns rays.
The hour angle is equivalent to 15 per
hour.
It is measured form noon based on the localsolar time or local apparent time being
positive in the morning and negative in the
afternoon.