What is the technique called where writer uses weather to reflect how a character feeling?

This technique is called pathetic fallacy. It's a literary device where the weather or natural elements are used to mirror or reflect the emotional state of a character.

Here are some examples:

* Stormy weather representing internal turmoil: A character struggling with a difficult decision might be faced with a raging thunderstorm outside, mirroring the emotional storm raging within them.

* Sunny skies symbolizing happiness: A character experiencing joy and contentment might be surrounded by bright sunshine and clear skies.

* Gloomy weather reflecting sadness: A character feeling down or depressed might be experiencing a dreary, overcast day, with the weather reflecting their mood.

Pathetic fallacy can be a powerful tool for writers to enhance the emotional impact of their stories and create a deeper connection between the reader and the characters.