I am new in telecomunications and this question just came up today and I coudn't find an explanation.
Here is the most common model for the ionosphere:
The ionosphere layer E is the main resposible for the reflection of the VHF signal which will allow communication over long distances during the day. But, during night, we don't have E layer because of the absence of the sun.
So, how does it happens during night? Does F2 layer became the main responsible for the reflection of the VHF signals?