Why should the rainbow be curved? Why can’t it be a straight line across the two horizons?

A rainbow is always curved just for the reason that all the angles of the water droplet have to be just right for it to reflect some light back to you, standing on the ground. So when there is sunlight behind a viewer, only those water droplets that have the same angle formed by the viewer, the droplet, and the sun (which is approximately 42 degrees) will produce the rainbow effect
A rainbow may look like a half circle when it is formed at sunrise or sunset because the light at that time travels almost horizontally towards the earth. However, as the sun rises high in the sky, the shape of the rainbow would be like an arch rather than a half circle.
Interestingly, from an airplane a rainbow is seen as a full circle

How are rainbows formed?

Sunlight is composed of light of varying wavelengths. Short wavelength light appears blue, violet and indigo, and long wavelength light appears red, orange and yellow.

When sunlight enters a raindrop in the air, the light splits into a multitude of colors. each rain droplet behaves like an independent prism which splits sunlight into its constituent colors.This light then reflects off the back surface of the raindrop and then goes back to the other side in which the light first passed, forming an arch. 


When light enters water it bends (refracts). The amount of bending depends on the wavelength of light. As a result, the light splits into its component colors.

useful links

some useful links...

http://nptel.iitm.ac.in/courses.php?branch=Ece


http://nptel.iitm.ac.in/video.php?courseId=1001&p=1

What would happen if there was no dust?

Without dust there would be less rainfall and sunsets would be less beautiful.


Rain is formed when water molecules in the air collect around particles of dust. When the collected water becomes heavy enough the water droplet falls to the earth as rain. Thus water vapor could be much less likely to turn to rain without the dust particles.


The water vapor and dust particles also serve to reflect the rays of the sun. At sunrise and sunset, when the sun is below the horizon, the dust and water vapor molecules reflect the longer, red, wavelengths of light such that we can see them for more time than any of the other wavelengths. The more dust particles in the air the more colorful the sunrise or sunset.

My Vision Board ....

want to see the whole world...  exotic places  like Australia,US ,Newzealand ,Switzerland ,Hawaii ..d list is endless 

.                                                           

                                                        Switzerland 

                                                                  

                                                                 Hawaii

                                                                  

                                                                   Malaysia     

                                                                  

                                                          london

                                                    

 my chains of hotels....some exotic hotels........

                                             

                                               my room     

                                            

                                                                 Hotel

My  exotic: house

                                                               Home 

                                                       exotic ...

                                                  Inside the house ..

My Cars like BMW ,AUDI , Ferrari ,Lamborghini ...

                                                    

                                                Audi R8...

                                                         
                                                            Porsche 918 Spyder

                                                   Bugatti Veyron

My Gadgets 

                                              Apple Mac Book                              Apple iPhone 3Gs          

How do referigerators work?

The basic mechanism of a refrigerator works like this:

1. The compressor compresses the refrigerant gas. This raises the refrigerant's pressure and temperature (orange), so the heat-exchanging coils outside the refrigerator allow the refrigerant to dissipate the heat of pressurization.
2. As it cools, the refrigerant condenses into liquid form (purple) and flows through the expansion valve.
3. When it flows through the expansion valve, the liquid refrigerant is allowed to move from a high-pressure zone to a low-pressure zone, so it expands and evaporates (light blue). In evaporating, it absorbs heat, making it cold.
4. The coils inside the refrigerator allow the refrigerant to absorb heat, making the inside of the refrigerator cold. The cycle then repeats.