What is red snow phenomenon ?

What is mirage phenomenon in hot countries?

A student observes the above phenomenon in the lab as a white light passes through a prism. Among many other colours, he observed the position of the two colours Red and Violet. What is the phenomenon called? What is the reason for the violet light to bend more than the red light?

What is the response of roots to gravity? What is this phenomenon known as ?

What is the response of stem to light ? What is this phenomenon known as ?