"WIND: A GIFT or A WRATH"

PART-2

Vayu’s father then switched on the laptop and inserted his 3G dongle into the port. Within few seconds he was online on the skype. After a minute or so Skype showed an incoming call from a person called David. Vayu’s father connected the call and said, “Hello David, how are you? Long time dude.”

“Hi Rajiv. I am perfectly fine. Oye Balle balle!” David said while raising both his hands in air doing traditional bhangra movement.

“Ha ha! What is this David? Are you learning Punjabi?”

“Ha ha ha! No no brother. It’s just that recently some Punjabi family has shifted in our neighborhood. Whenever we meet them they always say Balle Balle. Hence, I also said so. I must tell you Rajiv there are so many Punjabis shifting here from India. Canada is becoming mini Punjab. You also plan and come stay with us. It would be lovely.”

“Yeah! Sure David some day we will definitely come. Oh! I completely forgot. David this is my son Vayu and his friend Sarthak. Kids say hello to Uncle.”

“Uncle??? Rajiv do you think I am so old? I will not leave you. No need to call me Uncle, kids. Anyways how are you doing?”

“Hello sir. We are fine. It is nice to meet you.” Both Vayu and Sarthak said.

“Why are you both sounding dull? You should be more energetic. I will tell you a nice joke which will make you laugh.” David said.

“Wait David…. Do you remember Harshit, who had shifted to Australia last year?”

“The same lean guy with a moustache. How can I forget him? I have thrown ketchup on his shirt during our college days. Ha ha ha!”

“Yes yes that Harshit only. He is also calling me on Skype. Wait I will bring all three of us on conference.”

“Hello Harshit. How are you? What a pleasant surprise.” Vayu’s father said.

“Hey ya Rajiv. Hows ya? I am fine. Yeah! Dude, it has been a long time. Today I was a bit free so thought to call ya. What are ya doing?” Harshit said.

“Nothing much Harshit. Its good you called. You remember David who went to Canada, he is also on Skype. Wait I will add you in conference.”

Vayu’s father added him to the ongoing call.

“Hello Harshit bro how are you?” David said.

“I am fine dude. Hows ya? How’s the weather in Canada?”

 “It’s very cold here dude. Constantly snow is falling. You tell what about Australia?”

“Dude its very hot here. Send some cool air to Australia also. We are always sending wind to others but do not receive any.”

“Ha ha ha! Dude we ourself receive winds from countries like India. How can we send it to you?”

Both Vayu and Sarthak started laughing. They thought that David was kidding.

“You did not introduce me to these kids Rajiv.” Harshit asked.

“Oh! I am sorry. Harshit this is my son Vayu and he is his friend Sarthak.”

“Hello Kids. How are you and why did you laugh?”

“Hi Sir. We are fine. We laughed on the joke told by David sir about wind.” Both of them said.

“But kids, David is right they do receive winds. You don’t know this?” Harshit asked.

“No Uncle. Is it really true?” Vayu said and looked towards his father.

“Rajiv I am surprised to know that being a son of a great scientist they do not know the concept of Global Winds. Have you never told them?”

“No Harshit not till now.” Rajiv said.

“Ok. Doesn’t matter today we will explain them what are global winds and how are they distributed around the world. What say Harshit?” David said excitingly.

“Yeah dude sure why not.”

“It would be very nice friends.” Rajiv said.

“But let me first explain them about Coriolis force. It will take just 5 minutes. Stay on line. You both could also see and correct me where ever I am wrong.” Rajiv continued.

“Yeah! We will love to see your explanation. You always try to explain in different way.” Harshit said.

“Vayu go and bring football from the boot of our car. Meanwhile we will go to that merry-go-round.” Rajiv said pointing towards the Red and blue coloured Merry –go-round.

Vayu following his father’s order ran to the car to bring the ball. On the other hand Rajiv and Sarthak went to the Merry-Go-Round. Rajiv placed his laptop on a nearby bench with the camera facing the Merry-Go-Round so that both David and Harshit could also see. He then asked Sarthak to go and sit inside the Merry-Go-Round.

By now Vayu had also come carrying a football. He saw Sarthak sitting in Merry-Go-Round and asked his dad, “What is Sarthak doing there?”

“Wait Vayu you will get to know.” Rajiv said and took the ball from Vayu and gave it to Sarthak.

“Vayu go and stand a little far away. I will rotate this Merry –Go-Round.”

Vayu did as asked for. He moved few steps back from Marry-Go-Round.

“Now Sarthak I am going to rotate this Merry-Go-Round and when I say you have to throw this ball.”

“Ok Uncle.”

Rajiv rotated the Merry-Go-Round and when it came into motion, he told Sarthak to throw the ball. Sarthak threw the ball to the ground.

“Vayu what did you see? What path did the ball follow?”

“Dad the ball went in a straight line.”

“Nice. We will do this one more time.”

Rajiv did the same procedure again but this time he asked Sarthak, “Sarthak what did you see?”

“Uncle the ball took a curved path.” Sarthak said.

Vayu was surprised to hear his answer. He asked, “Dad how is it possible? I saw that ball fall in a straight line but Sarthak is saying he saw a curved path. Was I wrong?”

“No my child. You both are correct. What Sarthak saw was because of Coriolis force. Come let us join our Skype friends then I will explain you in detail.”

They returned to the bench and sat down, Rajiv keeping the laptop on his lap continued, “Children Coriolis force is a fictitious force i.e. a force which is actually an illusion. Moreover it only acts on a moving objects and only when you are taking measurements from rotating prospective. The same happen on earth. When on earth wind flows in certain direction the rotation of the earth on its axis causes the Coriolis effect on the wind and as a result wind deviates from the straight path and follows a curved path. Hence, when the rotation of the Earth causes the moving air and water to change directions it is known as Coriolis Effect. In the Northern Hemisphere of the Earth Coriolis force causes the winds to curve to their RIGHT and in the Southern Hemisphere it causes the winds to curve to their LEFT. I hope now you have got a basic idea of the Coriolis force.”

“Yes yes. We have.” Both the kids said.

“I must say that was a wonderful and the easiest explanation for coriolis force Rajiv.” David said.

“Thank you David for the appreciation.” Rajiv said smilingly.

“C’mon guys don’t forget the task. We have to explain them Global Winds not just Coriolis force. Let us do that. I have to go somewhere after half an hour.” Harshit said.

“Oh! Yes yes. David will you start or shall I?” Rajiv said.

 “I will start Rajiv.” David said excitingly. “Kids first of all you should know that there are 3 types of winds that we experience on Earth. One is Permanent or Global Winds that I and Harshit will explain and the other two are Seasonal and Local winds that Rajiv can explain you afterwards. Right Rajiv?”

“Aye aye Captain!” Rajiv said and all started laughing. Vayu and Sarthak were very excited as they were going to learn something new and interesting.

“Ok ok no jokes for next half an hour. Let us begin.” David said and shared a photo of Earth’s Globe on Skype so that all of them could see. “Ok kids, first tell me do you know how the hot air and cold air flows?”

“Yes Uncle. Dad had told us today only. Hot air being lighter rises up and cold air being heavier sinks down.” Vayu said.

“Very Good Vayu. And this concept is known as Convection. In simple terms Convection is the circular motion that happens when a warmer air or water which is less dense rises up and colder air or water which is denser sinks down consequently resulting in transfer of heat.” David explained.

“Ok now can you see this Globe picture I have shared here?”

“Yes Uncle.” Both said together.

“So can any of you tell me that in which part of the Earth receives maximum rays of the Sun and which part receives the minimum rays from the sun?”

“It’s easy Uncle. The equator will receive the maximum rays and the poles, both north and south, will receive minimum rays from the sun.” Sarthak said.

“Brilliant. I must say you both kids are very intelligent.”

“Thank you Uncle.” Both of them said blushingly.

“You are correct Sarthak. At the equator the sun rays directly hit making an angle almost equal to 90 degrees and at the poles the sun rays hit at a very small angle. That is the reason the Polar Regions are very cold and the equator is very warm.” David said.

Without waiting for anyone to say anything he continued, “I hope that you both know that our Earth rotates on its axis.”

“Yes Uncle we very well know that.” Both said in unison.

“So let us assume for some time that the Earth is still. God has stopped Earth’s rotation for some repair work.” David said and started laughing. With him every one else also laughed.

“No jokes David.” Harshit said with a wink.

“Oh! Yes. Sorry sorry. Now as we know that the Sun rays hit directly at the equator hence, the air present there is very warm. And at the poles the air is very cold. According to the concept of Convection we just learned that the warm air from the Equator rises up in the atmosphere to some level from where it will start moving towards the poles, both north and south, and the cold air from the poles sinks down and moves towards the Equator to form a Convection Loop or a Convection Cell. This happens at all areas of the Earth.” David said and showed them a picture depicting the movement of air.

“But actually this is not the case.” Harshit said. “You take some rest David. I will explain further.”

“Sure Harshit. Go ahead.” 

"WIND: A GIFT or A WRATH"

PART-1

Intellectual Minds, a smart school famous for its teaching methodology is located at the heart of the city Chandigarh. Every parent living in and around Chandigarh wants to admit their child in this school. Since past 10 years school has built up very good rapport. Moreover the students who pass from this school excel in various fields. The school has a very strong alumni base. Getting admission in Intellectual Minds is not easy. Parents as well as the children have to clear a rigorous interview test before getting admission. The school always takes cream of the children. The school does not lay burden on the children. Study is more practical than theoretical. It has a large open playground with latest gaming slides and equipments.

The time was 12 noon and lunch break was going on. Most of the children were playing in the play ground. Many were having their lunch. Weather was cool and cloudy. It could rain anytime but none of the children wanted to stay inside. Hence, everyone was in the play ground to enjoy the cloudy weather. All of them were very happy and excited except one student who was sitting under a tree and crying. His name was Sarthak. He was the most active student of his class but today his activeness was reduced to negative. He wanted to cry but fearing that anyone could see him he controlled his tears.

Vayu, his best friend saw him and ran towards him. “What are you doing here Sarthak? I have been looking for you all around. C’mon let’s play a game of football.”

“Sorry Vayu not today. I am in no mood to play football.” Sarthak said with moist eyes.

“Hey buddy! What happened? You are the most active student among us and you are saying you don’t want to play. Why? Is everything all right? Why are your eyes moist?”

“Nothing much dude it’s just that something is bothering me.”

“Oh! C’mon Sarthak you can tell me what is bothering you. I won’t tell anyone.”

“Thank you Vayu. You are my true friend.” Sarthak said and drank some water from his water bottle.

“Have you heard about Hudhud that recently hit Vizag coastline and has caused huge destruction.”

“Hudhud?” Vayu asked thoughtfully.

“Oh! Yes I remember. My father had told me that it is a type of tropical cyclone which is very intense and dangerous and mostly occurs in sea. But why are you asking?”

“You know what one of my cousin brothers was posted to Vizag by his company. On the day Hudhud hit Vizag he was in there only. And… And he lost his life Vayu due to the cyclone.” Sarthak said and started crying. “He was very nice Vayu. He used to love me a lot. I am not able to believe that he is no more.”

Vayu was in shock on hearing this. He hugged Sarthak and said, “Please don’t cry Sarthak. Everything will be fine. I know my words cannot cover your loss friend but I don’t know what should be said under such situations.”

“Hmmmmmm…..”

 “One thing I fail to understand. Our geography teacher says that cyclones, tornadoes are natural calamities. If they really are natural calamities why couldn’t God stop them from occurring? My mom says that God loves everyone then why these calamities occur?”

“Yes Vayu, you are right. I also fail to understand this. These calamities cause so much destruction but how are they actually formed? Is it really a natural phenomenon or something else? We should have asked our Geography teacher.” Sarthak said wiping his tears.

Bell rang indicating the end of lunch break. Everyone started moving towards their classes.

“C’mon Sarthak cheer up. Let us go to our class otherwise teacher will scold us.” Vayu took Sarthak inside the classroom.

At 2 o’ clock final bell rang and everyone packed their bags to go home.

On reaching home, Vayu saw that his father was engaged in some science project for his lab. Without saying a word he went to his room. His father saw this but ignored. When after 10 mins Vayu didn’t come out he went to his room and knocked the door.

Vayu opened the door and let his father come in.

“Vayu are you all right? Is there something disturbing you? Anything happened in school?” His father asked.

“Yes dad there is something which is disturbing me.” Vayu narrated the whole conversation he had with Sarthak that afternoon.

“Oh! Ok ok. You should not burden yourself with such things kid. C’mon take some rest and in the evening we will go to the town park. Ask Sarthak also to come along.” His father said and left the room.

Vayu just nodded and lied down on his bed not happy with his father’s response. He had thought his father will be able to explain the reason behind cyclones or tornadoes to him.

In the evening all of them went to the town park. Vayu’s father brought his laptop along with him. Vayu and Sarthak found a bench and sat down. Vayu’s father asked them to go and play like other kids meanwhile he will do some work. But none of them moved. It seemed as if they were not interested in anything. Vayu’s father then kept his laptop on the bench and took out a white paper.

“C’mon kids we will play something.”

None of them moved initially.

“Vayu come here and take this white paper from me.”

Vayu stood up least interested in the activity, went to his father and took the white paper.

“Ok now I hope you know how to make a paper plane. Can you please make one for me?”

Not understanding what his father was trying to do Vayu made a paper plane and gave it to his father.

“Very good Vayu, you have made a very nice plane. Now Sarthak could you come here please?”

“Sure Uncle.” Sarthak said and went to him.

“Hold this plate and stand 5 ft. away from Vayu.”

Sarthak did the same.

“Now Vayu take this paper plane and try to hit that plate.”

“What? It is so stupid to do this Dad. It is so easy.”

“If it’s easy then try it.” His father said.

Uninterested Vayu took the plane, aimed and threw it towards the plate. But to their surprise the plane didn’t even touched the plate rather it flew in different direction. Vayu looked towards Sarthak feeling embarrassed.

“What happen, Vayu? You said it was very easy. Ok, try it once again.” His father said with a smile.

Vayu again took the plane and aimed at the plate but this time he threw it with more force. Again the result was same. The plane flew away from the target. Both of the boys got confused and curious.

“Uncle what is happening? Why is Vayu not able to hit the plate even from a small distance?” Curious Sarthak asked.

“Because of Wind Sarthak. As you can see flowers are moving, leaves are moving and moreover our hairs are also moving. This is all because of a certain force present around us. And that is known as Wind. That is why when Vayu threw the plane the wind pushed it away because it is stronger than a paper plane.” Vayu’s father told them.

“Can you tell us more Dad?” Vayu requested his father. By now both the kids started showing interest.

“Yeah! Sure Vayu. Let us go to that pond.” Vayu’s father took them to the pond situated at the centre of the park.

“Now immerse your hand inside the pond completely and then bring it out. What did you notice?”

Vayu’s father asked Vayu.

“I felt as if something is pushing my hands down from top.” Surprised Vayu said.

“Correct. When you were trying to bring your hand out, water applied some pressure on your hand. Similarly like water air also presses our body with great force. But we never feel it because air presses our body from all sides and in turn our body exerts a counter pressure. This air pressure is present all around us. It changes with height and temperature. Ok now Sarthak you tell me have you ever seen anyone climbing a mountain or anyone diving deep in the sea?”

“Hmmm… Yes Uncle I have seen them on TV in Tom & Jerry cartoon where Tom wore a suit and jumped inside the water to catch Jerry.” Sarthak replied innocently.

“Ha ha ha! I didn’t know cartoons are so knowledgeable. That’s good. Do you know why Tom wore that suit?”

“No Uncle. Why?”

“Vayu can you tell us?”

“Nope.”

“Kids if Tom would have gone inside the sea without that suit he would have died.”

“Really? How?” Both of them asked in unison.

“Yes. This is because when one goes deep undersea the pressure increases tremendously that our body is unable to bear. In order to withstand that tremendous pressure that diving suit is very necessary. It also helps us to breath. Similarly a person climbing a mountain experiences a very low pressure. Hence, he also carries special equipments with him.”

“That means Dad on sea air pressure is high and on mountains it is low. Meaning air pressure decreases as we go up.” Vayu said.

“Brilliant Vayu. I am happy to know that you are so smart.” Vayu’s father said.

Vayu looked at Sarthak and smiled, feeling proud.

“Now let us consider two places in India. One is our place Chandigarh and the other let us take Simla in Himachal Pradesh. Can you tell me what the temperature in Chandigarh and Simla is? Which one is hotter?” Vayu’s father asked.

“Chandigarh is hot. Simla is cool.” Sarthak replied immediately.

“Very Good Sarthak. Now, in Chandigarh as the temperature is high the air gets heated up and hence rises up, creating a low pressure area. Whereas in Simla as the temperature is low the air gets cooled and heavy hence, it sinks down, creating a high pressure area. The air always moves from High pressure area to low pressure area. Hence, when there is snowfall in Simla we experience cold air here in Chandigarh as well.”

“But dad, why are you telling us about pressure? We had asked about wind not air pressure.” Vayu said getting curious.

“I know Vayu. I am coming to that only. So kids this movement of air from high pressure area to low pressure area is known as Wind. And it flows in all directions.”

Sarthak then started looking around in all directions. Something was disturbing him.

“What is it Sarthak? Do you want to ask something?” Vayu’s father said.

“One thing is bothering me Uncle. I looked around and saw that flowers are moving horizontally. Our hairs also move horizontally. The plane that Vayu threw also flew sideways. If wind flows in all the directions as you said then why don’t we experience it in vertical direction? Why didn’t the paper plane fly upwards?” Confused Sarthak asked.

“Ah! Very good observation Sarthak. It’s good you both are showing interest. But before answering the question I will tell you about some important forces which acts on air. One of them is Pressure Gradient Force and the other is Coriolis force. As I have told you earlier that the air pressure is different in different places. This difference in pressure produces a force. Hence, rate of change of pressure with distance is called Pressure Gradient. In turn this Pressure Gradient Force causes the air to move depicting the flow of wind. This force guides the wind to flow in various directions. Horizontal Pressure Gradients cause the wind to flow in horizontal direction and Vertical Pressure Gradient cause it to move in vertical direction. Now coming back to the question asked. When Pressure Gradient Force causes the wind to move up in vertical direction there is Gravitational Force, with which we are all aware of, that is caused by Earth’s Gravity, acts on the wind and tries to pull it down. This Gravitational Force is equal to the Vertical Pressure Gradient Force producing a Hydrostatic Balance or equilibrium. This is the reason we don’t experience wind in vertical direction. I hope you have got your answer Sarthak.”   

Sarthak gave a node in affirmative. With this Vayu’s father took out his mobile phone and started reading a text message he recently received. On reading the message he smiled and opened his laptop.

Vayu and Sarthak were discussing what they have learned today. After few minutes Vayu asked, “Dad what is Coriolis force? You didn’t tell about that.”

“I will explain about Coriolis effect after some time. Right now one of my friends from Canada has just sent me a message. He wants to talk to me on Skype. Let us talk to him. I will introduce you both to him. He is very nice. You will love him.”