Howdy! can be replied to with just a nod and a smile. It simply means Hi! in Texan - not How are you doing?. Or you might reply, Hey Y'all Doon? if you want to engage in proper Texan interactions. Replying in proper English, well pronounced, with each syllable clearly spoken, is HIGHLY discouraged.
The crest of a wave is the point of maximum positive displacement, or upward movement, away from equilibrium, or an undisturbed state. The opposite of crest is trough, which is the point of the greatest negative, downward displacement.
If a crest from one wave happens to line up with the trough of another, they cancel each other out. This is called destructive interference. If two waves line up crest to crest or trough to trough, they add up. This is called constructive interference. This is why waves at the beach are all different sizes. There are lots of different wave groups coming in, and theyâre interfering with each other in different ways.