What happens when the sunlight travels through the Earth's atmosphere?

When a ray of light travels from a denser medium to a rarer medium then

When light passes through a prism, it is:

The time taken to reach the Sunlight up to the surface of earth is approximately –

The streaming of light beams coming from the Sun through trees is said to have suggested that light travels in straight line. The particles on the path of light beams are visible to us because

Which of the following does not change when light travels from one medium to another?