Amines and esters will drift equally if you are talking about spray mist. Esters have a second factor of vaporizing and that vapor moving down wind to damage sensitive plants. High humidity, combined with high temperatures and no wind is extremely hazardous. You run the risk of creating a cloud of 2.4-D vapor that can permeate a large area. Grapes and tomatoes are especially sensitive. Metsulfuron is a very effective herbicide for pastures and hayfields. Observe the rate limitations on cool season grasses. 2,4-D will antidote some of the negative effects on the cool season grass as well as speed up injury to the weeds. However, if metsulfuron drifts, it is nasty. Most broadleaf crops are sensitive. I use all air inducted nozzles when applying broadleaf herbicides. No straight cut flat fans or flood jets. I will put an air induction venturi behind a flood jet if I want a boomless pattern. The rare day that it is hot, humid, and windless in Hawaii is a no spray day. I want 5-10 MPH not blowing towards desirable vegetation.
They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety.
Benjamin Franklin 1775
Sell not virtue to purchase wealth, nor Liberty to purchase power.
Benjamin Franklin Poor Richard's Almanac1738