Scientific view of Ira Sevaya at Sri Pada
by K. R. Abhayasingha

A view of Sri Pada
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The Sri Pada season started on December 1, 2009, the Uduwap Poya day.
It will terminate on the Vesak Poya day this year. Sri Pada Mountain is
also known by names like Samanala Kanda, (Samanala Mountain) and Adam's
Peak.
Every year millions of pilgrims, irrespective of their religion, join
processions to climb the Samanala Mountain to worship the footprint of
the Buddha. If it is not for worshipping, no one will climb the hill
particularly in the night. Even if one climbs the hill for personal
requirements he never spends the night hours on top of the hill.
For this reason, the pilgrims have a series of beliefs, expectations
and myths about their experience and sights of many events which are not
common in their day to day life. Even though all of them are natural
events, pilgrims understand them as events that occur only in the Adam's
Peak environment and many believe that such events have close
relationship to the footprint and the God Saman (Saman Deviyo).
The Ira Sevaya, (fluctuation of sun's images a few minutes before
sunrise) is one of the most beautiful and colourful visual observations
one can see in the world. When one observes the sky in the early morning
from the Adam's Peak, the eastern sky over the horizon changes its
colours very fast. So pilgrims can observe beautiful designs in the sky
and changes of colours just like the observations when he is in front of
an expert painter.
Mixed with all this colouring effect, the sun (apparently images of
the sun) can be seen above the horizon. It is not a single image, but
plenty of them. The images are seen in different locations before you
see the actual sun above the horizon a little later. One who does not
know what is really happening in the eastern sky, may believe that the
sun moves up and down several times to worship the footprint of the
Buddha as it is mentioned so in myths about Sri Pada. As it is not an
easy thing to count the number of visible images of the sun and most of
the pilgrims including some veteran Buddhist monks and learned
professors use to say that Sun worships three times the Buddha's foot
step before it rises. As the event could not be explained with
believable words not only the lay-pilgrims, but also religious pilgrims
including Buddhist monks still have belief of the God sun (Hiru Deviyo)
worshipping the footprint of the Buddha before it starts provision of
energy to the world.
It is pathetic to see that some media personnel, Buddhist monks and
learned professors taking part in television programs broadcast from the
Sri Pada still explaining this event to listeners without considering
the science behind these natural events.

Pilgrims at the sacred mountain |
This so called Ira Sevaya or the apparent movement of the sun before
sunrise is not a sight special to Sri Pada or Sri Lanka but it can be
seen from any hill top and also from airplanes, provided the clear sky
environment is available over the eastern sky and the observer is at a
significantly high altitude. I have heard that special locations on top
of hills in some parts of India have been reserved for tourists for them
to observe this beautiful scenery.
A light ray encounters a number of effects when it travels in a media
or passes a sharp edge, or travels through a common surface between two
transparent media like water and glass or air and glass or even
air-layer and another air-layer if two layers have different
characteristics. Such behaviours are explained under the terminology
like Reflection, Refraction, Diffraction, Scattering, Diffusion and
Total Internal Reflection which have meanings different from each other.
If one has studied these phenomena in Physics (Advanced Level or
higher levels), he can explain the science of the natural events like
rainbow, mirage, fluctuation of sun before sun rise, eclipses, halo
event and colourful pattern seen in the sky particularly in North Pole
and South Pole skies.
The apparent movement or shift of the sun a few minutes before
sunrise seen at the top of a hill is caused both by Total Internal
Reflection (TIR) and diffraction of sun's light beams by the lower
atmosphere.
Light rays go through Total Internal Reflection (TIR) when they meet
a common boundary between two media one denser than the other (like
glass and water, water and air or glass and air). Requirement for a beam
to undergo TIR is the incident rays should travel through the dense
medium before meeting the common boundary. When the incident angle
exceeds a particular value (called critical angle), rays are reflected
just like they are reflected by a plain mirror.
Light rays from the un-risen sun are incident through the dense air
which is at very low level, close to the earth surface, of the
atmosphere towards rare (low dense) layers which are above surface
layers. Under these circumstances, light rays get reflected towards the
dense layer at boundaries separating dense/rare air layers. Even though
the actual position of the sun at this time is covered by the solid
earth for an observer/pilgrim at the top of a hill like Sri Pada, he can
see the sun through the reflected light rays. The apparent positions of
the sun which are seen through reflected rays are images of sun and are
seen above the horizon (see the diagram).
As all of these happen while the sun and the earth are relatively
moving, an observer sees a large number of images of the sun when the
time passes and the apparent positions of images are not the same. The
observers may understand these changing of positions of suns images as
movement of sun up and down.
A few minutes later, the sun rises above the horizon and this is the
real sun. As the Total Internal Reflection does not occur now one can
see only one figure which is the real sun just above the horizon. This
position of the real sun is usually below the positions of the images he
saw a little early.
This phenomenon TIR is shown in the diagram. Please note that the
diagram is not drawn to a scale and is a little exaggerated to show you
the phenomenon clearly.
Ira Sevaya may be partly a result of the diffraction of solar light
beams at the tip of the earth in the early morning.
A light ray finds the body of the earth as a tiny sharp edge and
therefore it undergoes through the phenomenon diffraction at the earth
surface and breaks the ray into a number of branches which are
transmitted in different directions. Similar in TIR, a number of images
are formed by diffraction too and an observer on a high location can see
fluctuation of images of the sun again before sunrise. Both of these
phenomena, Total Internal Reflection and diffraction, may cause the so
called Ira Sevaya which is a natural event happening all over the world
every day. Both sun and earth are moving and rotating bodies. Sun is
common to the whole world and it provides energy to the whole world
positioning billions of kilometers away from us not close to Adam's
peak. Before it rises over the horizon seen from Sri Pada hill, it
spends hours in the sky in other parts of the world!.
Present day children should be directed in the correct way to
understand the real facts of our universe and other matters related to
it. Myths and beliefs will mislead the educating children and it is the
rights of all responsible personnel including lecturers, teachers and
also media personnel to highlight the truth about the natural events not
the myths. Otherwise the next generation will be never armed with
scientific understanding to face the present and future world.
The writer is former Director of Meteorology
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