Thor's Gift
Muhammad Ahmad
Award: Top 100
Award: Honorable Mention for Expert-Like
School: skaneateles high school
Teacher: daniel m. kurzen
Category: Natural
Photo #19405
Thor's Gift
One summer night in Murree, Pakistan, I sat with my cousins watching distant, bright lightning flashes–silent, without thunder. Later, I learned that I had witnessed a phenomenon known as heat lightning.
Heat lightning typically occurs from storm cells that develop 30-50 miles away on warm, humid nights. The warming air and cooling ground cause a temperature inversion in the atmosphere. Such inversions help refract light towards the ground and coincide with calmer air that stirs up less pollutants leading to less scattering of light. As a result, lightning from these far away storm cells can be clearly observed. The sound, however, fails to be audible farther than 10-15 miles due to attenuation, or the dissipation of the sound waves' energy due to scattering and absorption by the atmosphere.
Additionally, the silence of the storm was amplified by the differences in wave speed between light and sound. Light is transverse electromagnetic waves that self-propagate at about 300 million meters per second while sound is longitudinal mechanical pressure waves that travel at about 343 meters per second. Light's ability to travel nearly a million times faster than sound allowed the flash of lightning to hit my eyes almost instantaneously while the sound took minutes to cover the same distance, and in doing so became undetectable. This is why lightning always appears before thunder.
What appeared to be harmless lightning without the wrath of thunder actually showed that even nature's quietest spectacles speak volumes of physics.
|
