"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.

"WIND: A GIFT or A WRATH"

PART-4

Inside Vayu’s mother was watching TV. On seeing them she said, “Oh! Hello kids. You are back. Hello! Sarthak beta. How are you? I came to know about the loss of your cousin brother. I am really sorry beta.”

“Namastey Aunty. Yeah! It was very bad incidence happened in our family.” Sarthak said in a sad tone. By now kids were getting out of that tragic memory but Vayu’s mother brought them back. Vayu stared at her mother that why in the whole world she had to say this. Meanwhile his father also came inside and feeling the tense atmosphere he realized what would have happened. He looked towards his wife who was already feeling very sorry to bring the subject and said, “Darling you know what, Sarthak will be having dinner with us today and I have come to know that he likes Shahi Paneer very much. Would you please cook it for all of us?”

“Oh! That’s great. I was myself thinking to make paneer only. It will be very nice we all be having dinner together. Right Sarthak?” Vayu’s mother said trying to mend her mistake.

“Yes aunty.” Sarthak said in a meek voice.

“Come kids meanwhile the food is being cooked I’ll go and change and then we will play a small game. What do you say?” Vayu’s father said.

“Yeah! That will be great idea dad.”

Sarthak was still in thoughts.

“Ok then Vayu go and bring your G.I. Joes we recently bought.”

Surprised Vayu and Sarthak went to the room and brought the G.I. Joes.

“I don’t know what is Dad thinking of. Sometimes he does very weird things.” Vayu said to Sarthak.

Soon Rajiv came out of his room in night clothes and found that the kids were already on the table waiting for him.

“Ok kids let us begin the game. First of all tell me who wants to be from G.I. Joe gang and who wants to be from Cobra gang?”

“I will be from Cobra gang.” Vayu said instantly.

“Then Sarthak would be from G.I. Joe gang. Are you fine with it Sarthak?” Rajiv said.

“Yes Uncle.”

“Fine then Sarthak hold your best G.I. Joe ninja warrior that is Snake-Eyes who is master of many weapons and is also known as Wolverine of G.I. Joe. On the other hand Vayu will hold all time rival of Snake-Eyes that is Storm Shadow. Storm Shadow is the most powerful ninja among the Cobra pack.”

“Yooo Hoooo! I will kill you Snake-Eyes.”

“You will never succeed in your evil plans Storm Shadow.”

Both the kids were very excited on getting the best of the packs.

“Calm down kids the game is yet to begun.” Rajiv said.

“You must be thinking why we are playing this game. Am I right?”

“Yes dad. Why?” Vayu said.

“Vayu I am going to explain you the concept of Air Masses.”

“Air Masses? What is that Uncle?” Sarthak said.

“When the air remains over an ocean surface or over plains for sufficiently longer time it acquires the characteristics of that surface. This air with distinctive characteristics in terms of temperature and humidity is known as an Air Mass.”

Vayu and Sarthak started looking toward each other feeling bit confused.

“Wait kids, you both will get to know everything.” Rajiv said and further continued “As we know Vayu’s Storm Shadow is very dark and evil, we can say he is Cold hearted and on the other hand Sarthak’s Snake-Eyes is bright and helpful, we can say he is Warm-hearted. Similarly we have two Air Masses one is Cold Air Mass and the other is Warm Air Mass. Now let us mark an area or arena in which the fight will take place. In actual it is a land area surrounded by water and other lands from all sides. Now these Cold and Warm air masses can be further divided depending upon whether they are flowing over land or sea. Air Mass formed over land is called Continental Air Mass and Air Mass formed over sea or ocean is known as Maritime Air Mass.

Now, if they are coming from Polar Regions these air masses can be called as Maritime Polar air mass or Continental Polar air mass. On the other hand if they come from other bodies of land they are known as Maritime Tropical or Continental Tropical. Also Air coming from Polar Regions is very cold and air coming from Tropical Regions is warm. There is one more Air Mass that is formed over Arctic Region known as Arctic Air Mass. This is also a cold air mass.”

Vayu’s father took a brief pause and let the kids grasp. He then continued, “Ok kids let us begin the fight. Vayu’s Storm Shadow is Cold hearted we can call it Cold Air Mass. As we know that cold air sinks so the signature move of Storm Shadow is that it goes down on its opponent. On the other hand Sarthak’s Snake-Eyes is Warm hearted we can call it Warm Air mass. Now, as we know warm air rises so the signature move of Snake-Eyes is to come and rise over its opponent. C’mon kids let us begin the fight. 1…2….3 and Fight.”

“Here I come, Snake-Eyes. You are going to be history.” Vayu said excitingly.

“Not so soon Storm Shadow.” Sarthak said and plunges with equal force.

“Now as you both collide with each other you will be forming a front. Similarly when two air masses collide they form Fronts.”

Both of them started fighting with each other. The battle was very fierce. No one was ready to lose. Both Vayu and Sarthak were giving tough competition to each other.

“See none of you is ready to lose, this stage of the battle can be called stationery as no one is moving ahead. Similarly when Warm and Cold Air masses push each other but neither wins it is called as STATIONARY FRONT. This front causes several days of overcast weather and it drizzle.”

  

Sarthak’s Snake-Eyes then came from up which Vayu saw and kicked with his Storm Shadow to throw Snake-Eyes off balance and up in the air.

“Very good, Vayu that was a nice move.” Rajiv said.

Vayu started jumping in excitement as if he had already won. And Sarthak was feeling bad.

“Calm down Vayu the battle is not yet over. Now as you have beaten Snake-Eyes similarly cold air mass beats Warm air mass to form a COLD FRONT. Because of this Cold Front cumulonimbus clouds are formed in atmosphere which give birth to thunderstorms, hails, tornadoes or cyclones. We will be coming on to it after some time. Let us continue the fight.”

This time Sarthak came slowly with his Snake-Eyes from the top and sneaked over Vayu’s Storm Shadow and attacked Storm Shadow move thus winning the round.

“I must say that was a strong counter attack Sarthak.”

 “Thank you Uncle.” Sarthak said smilingly.

“Kids in actual Warm Air also sneak up the Cold Air in similar way covering whole of the Cold Air Mass and thus forms a WARM FRONT. Since warm air is slow hence, the Warm Front forms stratus cloud due to which there is drizzling for few days.”

“Come everyone dinner is ready. You can continue after wards.” Vayu’s mother shouted from the kitchen.

“Wait honey we are coming in 5 minutes. Let us finish the game kids. One last round. But we will make this round a bit difficult for our hero Snake-Eyes. We will be playing a 2-on-1 Handicap Match. What say kids?” Rajiv said.

“That will be fun Dad. Now I will definitely beat Snake-Eyes.”

“No ways Vayu. Snake-Eyes will win.” Sarthak said.

“That’s the spirit guys. Ok here take Cobra Commander with you Vayu. He is also cold in nature like Storm Shadow depicting another Cold Air Mass. Now, you are 2, Storm Shadow and Cobra Commander against Sarthak’s Snake-Eyes. Let us start.”

Vayu started with Cobra Commander and attacked Sarthak’s Snake-Eyes but Snake-Eyes being stronger then Cobra Commander it sneaked from up and took Cobra Commander in his signature move. Seeing his Commander losing Vayu brought his Storm Shadow inside the arena. He seemed to be really angry so he punched both of them up in the air thus winning the battle.

“Yoooo Hoooo! I won. I won.” Vayu said and started dancing.

Sarthak felt embarrassed that he lost.

“Yes yes Vayu you won. Now stop boasting.” Rajiv said. He then further continued, “Now in terms of fronts this is known as OCCLUDED FRONT in which two cold air masses beat one warm air mass as done by Vayu. Together these three masses form a scattered type of weather conditions. Sometimes its cloudy and sometime it rains but nothing too severe. These are all 4 types of fronts. Come now let’s have dinner otherwise Vayu’s mom will shout again.”

All of them went to the dining table where the food was already laid down. Vayu was still teasing Sarthak for his loss.

“Don’t worry Vayu next time I will win. You will see.” Sarthak said jokingly. With this all of them started their dinner. 

"WIND: A GIFT or A WRATH"

PART-3

“As we know that Earth is not still, but it rotates on its axis and that too from West to East, hence, causing an impact on the Global Wind Currents. What happens actually is that hot air rises from the Equator and flows towards the North and South Poles but at around 30 degree latitudes near the tropics the hot air losses some steam and begins to cool. Due to this the cool air now sink back to Earth surface and in turn returns to the Equator forming a small loop or convection cell. This cell is called Hadley Cell because the person who found this was George Hadley. Similarly around the Polar Regions, both in North and South, the sinking cold air which had started moving towards the Equator gains some heat at around 60 degree latitude or sub-polar latitude. Due to this it starts rising up in the atmosphere and in turn returns back to the Poles forming another convection cell. This cell is known as Polar Cell and I suppose the reasons are obvious. Isn’t it amazing kids? Wait let me show you a picture.” Harshit shared a picture showing Hadley Cell and Polar Cell.

“Sir truly it’s amazing. It’s hard to believe. But what happens in the middle of Hadley Cell and Polar Cell?” Sarthak asked in amusement.

“Oh yes. Kids, the Hadley Cell and Polar Cell create yet another convection cell in between. It is a moderate temperature cell which follows the similar pattern as the other two cells. This cell is called Ferrel Cell named after William Ferrel who actually found it.”

“This is completely amazing. Thank you sir for sharing this information with us.” Vayu said. Rajiv was also feeling happy by the fact that his friends have actually spared time to teach all this.

“Wait, there is some more. Let me tell you some more amazing things. The rising up of the warm air takes place all along the Equator and not just at one point. This had caused some problems in the earlier times for the sailors. Since the hot air all along the Equator rises up and flows towards the 30 degree latitudes this made equatorial region devoid of any horizontal wind, making it difficult for the early sailors to carry their sails. Hence, this region got his name as DOLDRUMS. Doldrums are a state of inactivity or stagnation. Similarly at around 30 degree latitudes both in Northern and Southern Hemisphere, sailors find it difficult to travel because the air there sinks down making the area devoid of horizontal wind. In earlier days Spanish sailors used to transport horses to their colonies in the West Indies or America. But due to no horizontal wind around these latitudes their voyage prolonged severely. This resulted in the shortage of water supply for keeping their horses alive. Hence, they started throwing the dead or the dying horses down into the ocean. This incidence gave the name HORSE LATITUDE to this region. In similar way region around 60 degrees latitude also do not receive horizontal winds. No special name is given to them. It is just known as Sub-Polar Latitudes. Apart from these regions the rest of the Earth receives at least some sort of horizontal wind. So kids these are the Global Wind currents. Moreover the Earth’s weather moves with these currents. Interesting right?” Harshit said.

“Very interesting sir.” Both said in unison and looked towards each other in amusement. No one had taught this to them before. In school they only get to know what was printed in book.

“I am amazed Harshit you know so much.” David said jokingly. “But you forgot to explain one thing.”

“What? Really? What is that Mr. Intelligent?”

“About how do Coriolis force acts on the winds.”

“Oh! Yes. But I have left only 5 more minutes than I have to go.” Harshit said feeling sad.

“Doesn’t matter dude. I will explain it. It will take just 5 minutes.”

“Oh! Really? Let us see.”

“So kids it may seem that the winds flow from north to south and from south to north as shown in the earlier pictures but this is not the case as the Earth is not still. It is rotating along its axis. This is where Coriolis force comes into action. Due to the rotation of the Earth the Coriolis force causes the wind to deflect from its path. As told by Rajiv earlier in the Northern Hemisphere the Coriolis force causes the wind to turn to their right and in the Southern hemisphere it causes the wind to turn to their left. Hence, in the northern hemisphere, between 30 degree latitude and the equator coriolis force causes the wind to flow from North-East to South-West direction. Since these winds were very helpful for European Sailors to travel to new America hence, these winds got their name as Trade Winds because of the boost they provided for trade between Europe and America. And flowing in the northern hemisphere they were called as North Easterly Trade Winds because they start from North East Direction. Similarly in Southern Hemisphere they were known as South Easterly Trade Winds because they start from South East Direction and moves to North West Direction.

Now moving up between 30 degree and 60 degree latitude as we know that wind here flows from Horse Latitude to Sub-Polar latitude, these winds also deflect from their path towards Right side in Northern Hemisphere and towards Left side in Southern Hemisphere. But since the Coriolis force is greater in these regions it seems as if winds are coming from West directions and flowing to East direction. Hence, these winds are called Prevailing Westerlies. These are the winds which cover entire US and Canada. Hence, did you see why I said that we ourselves receive winds?”
“Oh! Yes Uncle now we understood.” Sarthak and Vayu said.

“Good. Now moving further up and coming to the Polar Regions. As we know here in these regions the wind flows from Poles towards the 60 degree latitude or Sub-Polar Latitude. These winds are also deflected by the Great Coriolis force. Since these winds flow from East to West hence, these are known as Polar Easterlies. I guess now you know why these are called as Polar Easterlies.”  

“Yes, because they are present at Polar Regions.” Sarthak said.

“Yes Sarthak. With this we finish the concept of Global Winds. Like Winds Oceans also form various currents and cells but that we will tell some other time. Your Harshit sir might be getting late. See Harshit I finished it in 5 minutes.” David said teasingly.

“Yeah! Yeah! Whatever. Ok Kids we hope you have learned something today that you can tell your other classmates moreover to your teacher also. Ha ha! Now I will take leave. It was nice meeting you all. Thank you Rajiv for putting me into this conference otherwise I would have missed it. Take care all of you.” Harshit said and logged out.

“This guy I tell you. He is always in hurry. Anyways children now I will also go. We will talk some other time.” David said.

“Thank you David for giving us your time.” Rajiv said.

“Thank you so much Sir. We learned a lot today.” Kids said

“Oh! No need to thank kids. And Rajiv now you have to tell them about other winds.”

“Yeah! Sure David. Bye. Take care. Give our love to family.”

“Sure brother. Bye.” With this David also logged out.

Sarthak and Vayu started discussing whatever they had learned.

“C’mon kids it’s getting late. We will go back. Sarthak you also come with us. I will drop you back after dinner. We will inform at your home. On the way I will tell you about Local and Seasonal Winds.”

“Yippeee! You will be having dinner with us. I will ask mom to cook your favourite dish.” Vayu said enthusiastically.

On the way back home Rajiv said, “Vayu remember last summer we went to Pondicherry. Can you tell Sarthak and me what change we noticed in the weather there?”

“Oh! Yes. I very well remember Dad. Sarthak you know what we found there, the days used to extremely hot but the nights were very cold.” Vayu said.

“Really? How come?” Sarthak asked in amusement.

“Sarthak this is because of Local Winds. These winds cover a small area and only flow during a particular period of day or year. Land Breeze and Sea Breeze are type of Local Winds.”

“But how are they formed Uncle?” Sarthak asked innocently.

“I am coming to that Sarthak. As we have learned the concept of convection today, the same applies here too. Only difference is that both land and sea absorb and transfer heat differently. As we know sun rays heat the land surface faster than the sea because in the case of sea the rays of the sun travels deep down under the sea and the heating starts from the sea bed but in case of land it only has to heat up the surface. So during Day time land heats up faster and becomes warmer than the sea. And according to the concept of convection the warm air on the land becomes lighter and rises up creating a low pressure area. On the other hand air is cool above the sea so it sinks down creating a high pressure area. As we know wind flows from high to low pressure hence, here also wind flows from Sea to Land. This is known as Sea Breeze because it flows from the sea.”

“What happens in the night Dad?” Vayu asked.

“During night reversal takes place. The sea becomes hot because of the heat it had absorbed the whole day and the land becomes cooler than sea. Hence, during the night the wind flows from Land to Sea. This is called Land Breeze.” Rajiv said and took the last turn to reach their home.

“There is yet another type of winds called Seasonal Winds. When these Sea and land breezes flow over a large regions and change directions with the seasons they cause Seasonal Winds. Our favourite monsoon season is caused because of the Seasonal Winds only.” Rajiv continued. By this time they had reached to their house.

“C’mon kids, you go inside. I will park the car and come.”