Answer:
The sentence is fine as it is.
Step-by-step explanation:
The use of punctuation, such as the commas and period/ full stop greatly affects how a sentence is structured and taken. It can also completely change what the sentence means.
In the given sentence, the use of the period or separation of the sentence into two is not necessary as the sentence is fine as it is originally put. There is no need to separate the sentences as that will change the meaning of the sentence. The phrase "Tomas laughed and pointed at the sky" is an independent clause while "when he saw the sun start to poke out of the clouds" is a dependent clause. But at the same time, the dependent clause can't stand on its own as a full sentence, and therefore needs the independent clause to be a full, meaningful sentence.
Thus, the correct answer is that the sentence needs no change and is fine as it is.