## Estimating the Distance of a Lightning Strike

###### By Anupum Pant

Everyone who’s studied basic science at school knows that light travels much much faster than sound. Light can travel about 300,000 km in a single second. Sound, in the same time would cover about 0.3 km. That’s a huge difference.

Considering that, it is fairly easy to calculate how far a lightning strike happens by measuring the time it takes the sound to reach you after you see the lightning. In that case, taking into account the enormous speed of light, you assume that the light instantly reaches you and you just count the seconds it takes for the sound to be heard at the place you are.

Then multiplying the seconds with 0.3 would give you, in kilometres, how far it happened – an estimation of, course.

So, if there isn’t a mess of lightning strikes happening somewhere, which usually isn’t the case, and if you can clearly tell which sound came from which lightning strike, which you can’t in most cases, you can actually estimate the distance of a strike very easily.

If you think that’s great. You might be interested in:
How to estimate the temperature.
and How to estimate the time to sunset.

## Singing Sand Dunes

###### By Anupum Pant

I cannot say why you’d do it, but suppose you were on a hike to the top of a 120 feet sand dune in the centre of some desert, say  near Al-Askharah, a coastal town in Oman. Unfortunately, it’s also the mid summer time, with 50 degree Celsius winds blowing at 50 miles an hour, and the dune you are climbing has a slope of 30 degrees. There’s nothing else (besides sand) to be seen or heard for miles around you.

The numbers are apparently perfect for a very eerie phenomenon to occur. And then the whole desert suddenly cries out a booming chorus of a very low hum (Like someone playing a very low note on the cello). What could have possibly caused that?

For ages such sounds in the midst of empty deserts have been bewildering people. Marco polo mentioned it. Charles Darwin also wrote about the “Bellower” in The Voyage of the Beagle. Moreover, until recently, even modern scientists weren’t sure what caused these sounds. It was only during the year 2009 that things started becoming clear when a group of researchers started experiments with sand on an incline in a laboratory environment.

The low droning hums, now as we know, come from within the sand dunes. The Sand particles are blown by the wind, causing an avalanche. As the sand falls across the 30 degree incline of the dune, they vibrate, synchronise and send the vibrations into the dune. The dunes pick up these tiny synchronised vibrations and amplify them, causing the low droning hum; coherent enough to resemble musical notes.

This only happens at few places around the world. In Morocco the dunes cry out an echoing hum of 105 hertz. Whereas in Oman the sands create a mixture of frequencies ranging from low 90 to slightly less low, 150 hertz. Something similar is also heard in the death valley. The video explains…

## Screaming Coin and a Singing Spoon

###### By Anupum Pant

Dry ice, or Cardice – as British researchers call it, is a solid form of carbon dioxide. When carbon dioxide is cooled below temperatures of -78.5 degrees centigrade, the gas gets directly frozen into a solid form. -78.5 degrees centigrade is extremely cold, and handling dry ice without proper protection can be very dangerous – could cause frostbite / burns. The point being, it’s extremely cold.

Since it’s too cold compared to something at room temperature, even everyday objects at room temperature can make it vaporize. A simple metal coin at room temperature would feel like a hot pan to dry ice. So, when a coin is shoved into a piece of dry ice, it creates a funny sound, just like water would, on a very hot pan; or, you could say the sound be very much like a hot metal ball being dropped into a cold bath of water (the temperature difference being much less in this case, of course).

This is how it works: The metal piece at room temperature vaporizes some amount of carbon dioxide from the piece of dry ice when it comes in contact. There’s a pressure difference (Bernoulli’s principle) associated with this process and the gas tries to escape. This makes the metal vibrate very fast, creating that funny sound. This is how it sounds…

Metals work best because they have a good thermal conductivity. For the sake of trying it out yourself, if you have a piece of dry ice lying unused, you could dip a spoon in hot water and make it touch the piece of dry ice. A slightly warmer spoon will probably give you a better effect. And then the spoon will be singing…