Sunlight passes into a raindrop at an angle of 22.5° from the normal at one point on the droplet. what is the angle of refraction?

The angle of refraction is 16.7°

Explanation:

The Snell´s law is:

(sinθi/sinθr)=nr/ni

Where θi is the angle of incidence, θr is the angle of refraction, ni is the first refractive index and nr is the second refractive index. Clearing θr:

θr=sin^-1((ni*sinθi)/nr))=sin^-1((1000*sin22.5)/1.333)=16.7°

conduction, convection, radiation