Nces Solar

7/28/2019 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.

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