There are a few different potential reasons why some people experience a sense of happiness or contentment when it rains. These may include:

• The sound of rain: The sound of rain can be soothing and calming for some people, particularly if it is accompanied by a cozy atmosphere, such as being inside a warm, comfortable home or wrapped in a blanket. The sound of rain may also be associated with feelings of relaxation and rest, which can contribute to a sense of happiness or contentment.
• The change in weather: For some people, the arrival of rain may signal a change in the weather and a break from the routine of everyday life. This change can be refreshing and invigorating, and may lead to feelings of happiness or excitement.
• The opportunity to slow down: Rainy days may provide an opportunity to slow down and take a break from the hustle and bustle of daily life. This can be particularly appealing for people who live in fast-paced or stressful environments. Taking time to relax and unwind can be enjoyable and may contribute to feelings of happiness and contentment.
• The aesthetics of rain: Some people may simply enjoy the look and feel of rain, such as the way it makes the air feel fresh and clean, or the way it can create beautiful reflections on puddles or other surfaces. The aesthetic appeal of rain may contribute to feelings of happiness or joy.

It is worth noting that people’s experiences and emotions are subjective, and what brings happiness or contentment to one person may not have the same effect on another. It is also possible that people may associate rain with positive memories or experiences from the past, which can contribute to their feelings of happiness when it rains.