Why is "at" used in following sentence :
The children with their yellow hair hollered at the deep dome of Martian sky?
I think "under" would be the better preposition to be used, wouldn't it?
The prepositions "under" and "at" mean two different things. Consider:
We shot arrows under the full moon.
We shot arrows at the full moon.
In the first sentence "under" means we were doing archery when there was a full moon and doesn't explain which way our arrows went. In the second sentence, "at" means that we aimed our arrows toward the full moon.
The children with their yellow hair hollered at the deep dome of Martian sky. There was no answer but the racing hiss of wind through the stiff grass.
When people yell at the sky there is a sense of directing your voice at something intangible or at the entire universe. So the children weren't just running around on Mars hollering at nothing, they were yelling toward the sky. It might be interpreted as yelling at the planet to see if it would answer them back.
Here's another example:
Honestly, I think you may as well throw up your hands, yell at the sky about how dumb life is, and then keep using Curse.
From a forum thread where someone was looking for a replacement for a piece of software named "Curse"
Yelling/hollering/screaming at the sky is a way of saying let your emotion out without directing it at someone or something in particular.
"holler" is a verb that means "to shout loudly"
"holler at" means "to shout at someone/something". There is often a sense of aggression when we "talk at", "shout at", "holler at" someone of something. This is also typically a one-sided communication.
"holler under" means that someone/something was situated under something (or someone) and shouted loudly.
"holler to" is also possible. In that case, the person you are hollering to is typically far away. You are trying to send a message across a great distance, so you must holler.
Edit: Holler as the intransitive verb means "give a loud shout or cry" and "holler at" [US - usually in imperative] means "to make contact with someone/something; to contact someone/something" so we might interpret the sentence "The children hollered at the deep dome of Martian sky" in two ways:
Both of which can be comprehended uniquely.