"WIND: A GIFT or A WRATH"

PART-5

While they were having dinner Rajiv’s cell phone rang. It was Sarthak’s father calling. He picked up the phone. After ending the call he said, “Sarthak it was your dad. He said that he and your mother are going somewhere for some urgent work. It will take around half an hour. So I should not drop you back they will themselves pick you up from here.”

“Ok Uncle.” Sarthak said.

“That means you are here for another half an hour. Yiippeee!” Vayu said enthusiastically.

“Quickly let us finish our dinner then we will think how to utilize this half an hour.”

After finishing their meal they both went to the hall and decided to watch cartoon movie coming on TV. While they were watching Vayu’s dad came with two 2 ltrs empty coke bottle in his hands and kept them on the table in front of them.

Eager vayu said, “Dad what are you doing?”

“Just wait Vayu you will get to know everything but first bring one bowl full of water. And Sarthak will you please switch off the TV.”

“Sure Uncle.”

Meanwhile Vayu brought the bowl of water and gave it to his dad. Rajiv then poured the water into one the bottle and closed it. The water half filled the bottle.

“Dad, why have you drilled holes on both the caps?”

“Wait Vayu.”

Rajiv then placed the empty bottle on the table and the half filled bottle on top of the empty bottle such that both the caps touch each other. He then taped both the caps together.

“Kids now you are going to see a magic.”

“Magic… Wow!!” Both said.

Rajiv then held the upper bottle and gave a small swirling motion to the bottle. The kids saw that the small swirling motion started rotating the water inside the bottle forming a cyclone like structure. The hole drilled in both the caps caused the water to drip down to the empty bottle.

Both Vayu and Sarthak were astonished to see this. “What was this Dad?” Vayu asked

“This was a small experiment to tell you the shape of a cyclone.”

Before Sarthak could drift back to the memory of his cousin, Rajiv continued, “Sarthak, Vayu told me that when in the morning you told him about the tragic incidence of your cousin’s death in Hudhud you both in a way blamed God for not stopping these natural calamities from occurring. But kids this is not the case. Although these are natural calamities and no human can do anything to stop them our God is also innocent. He can never see his own creation dying like this.”

“Then why such calamities occur, Uncle?” Angry Sarthak asked.

“They occur because of certain changes in the environment.”

“What kind of changes Dad?”

“Yes, I am going to tell that only. And now when you both are aware of the concept of wind and you also know what Coriolis force, air masses and fronts is, I am sure you will be able to understand whatever I am going to tell you within next 15 minutes. But first you have to promise that none of you will interrupt me in between. Especially you, Vayu.”

“Fine Dad. Now tell us.”

Rajiv then powered his laptop and showed them the map of India with Indian Ocean surrounding it. “As you can see our Indian coastline is surrounded by Indian Ocean with Bay of Bengal on Eastern side and Arabian Sea on Western side this is naturally prone to cyclones like Hudhud or Tsunamis. These calamities are called with different names in different regions like in Indian Ocean they are called Cyclones, in Atlantic they are called Hurricanes, Typhoons in Western Pacific and South China Sea and Willy-willies in the Western Australia. But the uniform name is Tropical Cyclones. These types of cyclones are very destructive in nature and are formed only over the seas and on reaching the land they dissipate.”

Rajiv then showed them the picture of Eastern coastline and Bay of Bengal and further continued, “Now kids before we see how a cyclone is formed we should know certain conditions that are necessary to form a cyclone. Cyclones get their energies only from warm seas hence the temperature of the large Sea surface should be above 27 degrees also it should be a weak, low pressure area. Another necessary condition is the presence of Coriolis Force and also there should be small variations in the vertical wind speed. Now as we know the rules let me show you how cyclones form.”

Rajiv then switched on a video he had created and said, “Let us suppose this is Indian Ocean and the temperature of the surface is continuously rising. The temperature is now 27 degree centigrade. Now as we know the damp warm air above sea surface will rise and will meet the cold air present in the atmosphere. Also we already know about Cold Front. Can any of you tell me what was Cold Front?” He paused the video.

“Oh! Yes Uncle how can I forget that. Vayu beat me in that round. In Cold Front the Cold Air Mass beats the Warm Air Mass causing the warm air to move up in the atmosphere forming a Co… co…lumbus clouds.” Sarthak said.

“Ha ha ha! Not Columbus Sarthak it was cumulonimbus clouds. Doesn’t matter, I am impressed that you remember. Now kids, remember I also told you that the Cold Fronts lead to the formation of tornadoes, cyclones, etc.”

“Yes yes.” Both said.

“When the cumulonimbus clouds are formed by Cold Front they cause heavy rains. Now let us continue our video.” Rajiv said and continued, “This condensation process or change of water vapor to water droplets in the form of rain produces Latent Heat which further warms the atmosphere and make it more buoyant. Due to this the air rises more rapidly forming more thunder or cumulonimbus clouds.”

Rajiv then showed them how the clouds were formed.

“But Dad how can these be so devastating that they can destroy entire city?”

“Vayu I am coming to that. It’s just the beginning kid.” Rajiv said and continued the video.

“Now we know what Coriolis force is and what effect it has on the wind. Right kids?”

“Yes Uncle. We know that.” Sarthak said.

“Now as the trade winds arrives the Earth’s surface they curve and change their path due to Earth’s Rotation causing Coriolis Effect. Due to this winds coming from South curve to their right that is towards East and winds coming from North curves to their right that is towards West forming a pattern of spinning tropical storm, as you can see in this video. As the storm grows larger more moist warm air is drawn towards the surface. This in turn produces more water vapor that forms clouds which in turn forms more water droplets and thus producing more Latent Heat. This Latent Heat continuously gives Energy to the storm helping the storm to increase its speed of rotation. This is how a tropical storm is formed. See this video.”

“But Uncle when does this storm becomes a cyclone?” Sarthak asked eagerly.

“You kids are so eager to know everything. Give me a break kids. Atleast give me a second to breathe.” Rajiv said smilingly.

“Oh! Sorry Uncle but I was worried that my parents will come any time and then I have to go. I don’t want to miss this.”

“We still have 5 minutes Sarthak till your Parents arrive. It’s just the ending now.” Rajiv said and drank some water. He then continued, “So kids when the speed of this rotating tropical storm becomes more than 74 mph it officially falls under the Category 1 Cyclone. If its speed reaches above 96 mph it falls under Category 2 Cyclone. Hence, with increase in speed of rotation the category keeps on changing and with it the wrath of the cyclone also increases. The most dangerous of all is the Category 5 Cyclone with rotation speed more than 157 mph. This is the last category of the Cyclone and it could be very devastating. Now let me tell you what exactly happens inside the cyclone.”

Rajiv then changed the video and said, “We have seen before that the moist warm air rises to form thunder clouds. As the air cools above it becomes denser and falls down. This as you can see here forms an alternate pattern of warm air rising and cold air sinking. In other words this process forms alternating storm clouds with white slots in between. This produces spiraling rain bands that we see in the satellite pictures of cyclones taken from above. These spiraling storm clouds are known as Eye Walls and in the center is the Eye of the Cyclone. Eye Walls are the most destructive part of the cyclone and all the destruction caused is only because of this Eye Wall. On the other hand in the Eye of the cyclone the wind drops to give rise to an airy calm.”

“No wind in the Eye at all?” Shocked Vayu asked.

“Yes my son the Eye of the cyclone is quite calm. Now as the cyclones are formed from warm damp air when they reached the coasts they start sucking dry air hence, start losing their power. This is the reason why tropical cyclones are formed overseas and not over lands. I hope you have understood the concept kids. And now you both know how Hudhud was formed.”

“Perfectly Uncle. You know what initially when you were telling us about wind in the park I thought it as a Gift of God but know I think it is a Wrath because of the destruction it causes.”

“Ha ha! It completely depends on us how we want to look.”

“What do you mean dad? Are you saying that cyclones can be good as well?”

“Yes that is what I am saying Vayu.”

Confused kids looked towards each other thinking that Rajiv has gone mad.

“See kids every coin has two sides. Cyclones are actually very important even though they are deadly. Cyclones help in balance out the temperature across the Earth. They act as equalizers that take heat energy from the tropics and transform them into colder climates when the environment requires.”

“Really?? That’s even more surprising. I am more confused now whether to consider winds as a gift or as a wrath.” Sarthak said.

Suddenly loud horn of a car came. Sarthak’s parents had arrived on the right time. Sarthak stood up hugged Vayu and was ready to go when Rajiv said, “Don’t think too much Sarthak. Just remember whatever you have learned today that’s important.”

“Sure Uncle. Thank you for your today’s efforts. We have actually learned a lot that we will never forget.” Sarthak said and bid them goodbye.

“Bye Sarthak.” Rajiv said.

“Bye Sarthak. We will meet tomorrow in school.” Vayu said and went inside.