Why Does a Liquid Jet Break into Droplets?

The science of droplet formation

A jet of glycerol 50 % v/v (aqueous solution) breaking into droplets. The solution is dyed green. (Credit: Bill Hammack)

A smooth jet of water coming out of a slightly open kitchen faucet and breaking into droplets is a familiar experience. The droplet formation happens at a certain distance from the faucet. Why does a water jet break into droplets? Why can’t it just stay as it is? Bill Hammack (EngineerGuy) has an excellent video on this phenomenon (I…