What does Rossby and Kelvin wave mean? - A Layman type Explaination

What does Rossby and Kelvin wave mean?

You would have heard these names in weather forecasts. I will try to keep this post simple. Please try to give a read. It may be useful even for IAS, UPSC and some govt exam aspirants.

Refer the Pictures below for clear understanding

Remember:

Rossby wave move from East to west
Kelvin wave move from West to East

Both moves in opposite direction to each other. These waves are called Planetary waves because it happens due to the rotation of our planet.

How does it form and what impact it does?

Equatorial Kelvin wave is caused by wind at surface level in the ocean and also due to convection (Transfer of heat) etc. near the equator. It is trapped at the equator due to Coriolis force. So it can only move from west to east. Though it never makes a direct impact on Cyclone Formation. It alters the Sea Surface Height (SSH) and Sea Surface Temperature (SST) important for the development of Cyclones.

It causes Upwelling (cold underwater rising to the surface) and downwelling (Sinking of hot water to the bottom of ocean waters). Fani Cyclone was a Kelvin wave trigger.

Equatorial Rossby wave is generated by Kelvin wave refraction and it moves in the opposite direction. If you see two low pressures connected on either side of Equator it's
generated by Rossby wave. Also, they are connected with the MJO movement.

Rossby-gravity wave this makes upper divergent flow and exchange energy between North and South hemisphere belt type of Low Circulation pattern.

Key Points take away:

Kelvin: Single centres of low and high pressure along the equator

Rossby: Parallel lows and high circulation on either side of the
equator (Spilited from Kelvin wave)

Mixed Rossby-gravity wave: Belt type of Low and high Circulation on either side

There are many types in this topic, If you want those comment below I will try to make a more detailed post in Blog. This Topic is made as per request

You can track the movement of Kelvin, Rossby, MJO waves in this site: http://mikeventrice.weebly.com/cckwmjo.html

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