Question tags-use

Mary: It’s a lovely day, isn’t it?
Joan: Beautiful. We’re having a glorious summer, aren’t we?
Mary: You haven’t heard a forecast for the weekend, have you?
Joan: No, I haven’t, but I think it’s going to stay sunny.

A question tag is a short question added on to a statement.
When a tag is spoken, the voice can go up or down.

FALLING                 ↘
• It’s a lovely day, isn’t it?
With a falling intonation the speaker thinks the statement is true. Mary knows that it is a lovely day, and she is inviting Joan to continue the conversation. The tag is not really a question.
RISING                                          ↗
• You haven’t heard a forecast, have you?
With a rising intonation the speaker is less sure. Mary doesn’t know if Joan has heard a weather forecast or not. The tag is more like a real question.