Physics of Cyclones

         Cyclones are the most violent storms on earth. They are also called hurricanes, typhoons and willy willies depending upon their locations on earth. Geographically these all storms are called tropical cyclones. Tropical regions receive vertically and direct sunrays whereas polar regions receive slanting sunrays. Wind movements are determine by high pressure and low pressure system. Winds always move from high pressure to low pressure areas. The differences in atmospheric pressure create pressure gradient causes the wind to move. Low pressure occurs where land or ocean is warm and high pressure occurs where land or ocean is cool. That’s why winds blow from polar region (cool land) to equator (warm land).

     Another factor which is important in the formation of cyclones is CORIOLIS FORCE. Due to the rotation of earth, a force is generated and it acts perpendicular to the direction of motion and to the axis of rotation. Earth is spherical and it moves from west to east and also, earth is much wider at the equator than at the poles. So, if anything has to be come straight from the poles to the equator it gets deflected towards right in northern hemisphere and towards left in southern hemisphere. Such deflection is caused by coriolis force.

At the centre of every cyclone there is region of low pressure called eye of cyclone. As air moves from high pressure to low pressure which means outer region of cyclone consists of cool air which surrounds low pressure area of cyclone. Warm and moist air rises from the surface of ocean. As it rises, to fill its place cool air rushes to this low pressure region. Now this air becomes warm and moist and this rises too and hence warm air continues to rise. Temperature drops at high altitude, so warm air cools off to form clouds. Now coriolis force comes into factor, as air deflected to right in northern hemisphere but it got attracted to eye of storm (low pressure region) this makes it swirl in anticlockwise direction. Similarly in southern hemisphere due to bending in left side it swirl in clockwise direction.

Cyclones normally occur on the ocean surface due to continuous supply of moisture. When it hits the land, moisture supply cut off and storm dissipates.

Bose Einstein Condensate- our fifth state of matter

We all were well studied about four states of matter - solid, liquid, gas and plasma. There is also fifth state of matter which is much mysterious and is called Bose Einstein Condensate. It is a state of matter in which atoms and subatomic particles are cooled to absolute zero temperature (0K). At such low temperature, they have no free energy to do any random movements. At this point, they clump together and the whole group starts behaving like as though it were a single particle. This form of matter was discovered by Albert Einstein in 1924 on the basis of the formulations derived by the Indian physicist Satyendra Nath Bose.

To make bose Einstein condensate, scientists used atoms of rubidium. Then cooled them with laser, this takes away all their energies by imposing radiative pressure. After that, cooling of atoms starts which was further supported by evaporative cooling. In 1990s Cornell and Wieman succeeded in merging together 2000 individual atoms and called it superatom. Superatom is nothing but a large condensate enough to be viewed by a microscope also.

BEC theory has traced back to 1924, when Bose observed that there are two classes behave differently. Fermions tend to avoid each other and each electron in a group occupies different quantum states. Whereas there are bosons also in which can share number of particles share single quantum state. Einstein extended this work and named such particles as ‘bosonic atoms’ which have even spins and they collapse together to exist in single quantum state at absolute zero temperature. At that time there was no method to attain such low temperature, that’s why we waited so long until 1990s.

BEC is related to two interesting phenomena: superconductivity and superfluidity. Superconductivity- in which electrons move through material with zero electrical resistance and superfluidity- in which helium isotopes forms liquid that offers zero friction.

APPLICATIONS

•  Can be used for the detection of gravitational field intensity.
• It can be combined with atomic lasers to create high precision nano-structures.
• It is used in the study of cosmological phenomena by undergoing various simulations.
• Applications in superconductivity and superfluidity.
• It deepens the knowledge of quantum mechanics.