Explain the process that causes dew to form on blades of grass?

Condensation causes dew to form on blades of grass because the water molecules that were in the air were excited because they were heated, and when the surroundings became cooler, the molecules calmed down and condensed into liquid.

Heat is radiated, atmospheric moisture condenses at a rate greater than that at which it can evaporate, resulting in the formation of water droplets.