Is it necessary to write the prefix 'hin' in the sentence? Will it change the meaning of the sentence if it's added ?
First of all you need to drop
What do you want to say?
The cloud is moving northwards?
The translation by adibender
is suitable then.
An old-fashioned translation for this meaning would also be:
gen originates from gegen and means towards (the north).
But what about the translation from your question?
This one is also correct, but means something different: The cloud isn’t moving northwards, it is stretched in a northern direction. In this case, hin is also optional but if used it emphasizes this meaning (might differ locally).
sich ziehen is used to express the following: