Why shorter particles scatter light of shorter wavelength more effectivEly than larger particles and vice versa??

Shorter wavelength = more interactions with the air per centimeter = more scattering.

Example

Two people are riding bikes at the same speed. One taps her left foot on the ground every 20 feet, the other taps his left foot on the ground every 5 feet. The 5-foot-tapper turns more left quickly - just as shorter-wavelength light turns more quickly.