The Sri Pada season started on December 1, 2009, Unduwap Poya day. It will end on the Vesak Poya day this year. Sri Pada is also known as Samanala Kanda (Samanala Mountain) and Adam's Peak and every year millions of pilgrims, irrespective of their religion climb the Mountain to worship the footprint of the Lord Buddha.
Pilgrims have many beliefs and expectations about what they will experience and see at the peak. Even though all of them are natural occurences, pilgrims view them as events that occur only in the Adam’s Peak environment and many believe that such occurences have a close relationship to the footprint and God Saman (Saman Deviyo).
The Ira Sevaya (fluctuation of the 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 Adam's Peak, the eastern sky over the horizon changes colour very fast.
Mixed with all these effects, 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 in many myths about Sri Pada. Pilgrims including some veteran Buddhist monks and learned professors say that the sun worships the Buddha’s footprint three times before it rises.
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 can be seen from any hilltop and also from airplanes, provided there is a clear sky over the eastern sky and the observer is at a significantly high altitude. A light ray encounters a number of effects when it travels 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 an air-layer and another air-layer if two layers have different characteristics.
Such behaviour is explained under terms like Reflection, Refraction, Diffraction, Scattering, Diffusion and Total Internal Reflection which have different meanings.
If one has studied these phenomena in Physics he can explain the science of the natural events like rainbow, mirage, fluctuation of sun before sun rise, eclipses, halos and colourful patterns seen in the sky particularly in the North Pole and South Pole.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 the 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). For a beam to undergo TIR 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 rising 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 the 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 as time passes and the apparent positions of images are not the same. The observers may understand these changing positions of the sun's images as movement of sun up and down.
A few minutes later, the sun rises above the horizon. 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 sun is usually below the positions of the images he saw a little earlier. (This phenomenon TIR is shown in the diagram. The diagram is not drawn to a scale and is a little exaggerated to show 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 to 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 sun rise.
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.
Children should understand the real facts of our universe and other matters related to it. All responsible including lecturers, teachers and also media personnel should highlight the truth about the natural event not the myths or the next generation will be never armed with scientific understanding to face the present and future world.
The writer is a former Director of Meteorology. He can be reached on Tel: 081-3800083 or email: