Why do rainbows appear in summer?

This is mainly because there are frequent thunderstorms or showers in summer, and the scope of these rains is not large. It is often raining in the sky here, and the sky over there is still shining with strong sunshine. After the rain, there are still many small water droplets floating in the sky. When sunlight passes through these small water droplets, beautiful rainbows appear in the sky through reflection and refraction.

In winter, the weather is generally cold, the air is dry, and there are few opportunities for rain and showers. Most of it is snowfall, and snowfall does not form rainbows, so rainbows are unlikely to appear in winter. But in rare cases, rainbows may appear when there are suitable conditions to form rainbows in the sky. Why is the rainbow curved?

Every drop of water in the water mist can be refracted, but for the observer on the ground, the water drops that meet the conditions, that is, refracted light, can be seen by the observer, only distributed on a concentric circle centered on the observer's eyes. When the observer's position changes, the positions of these qualified water droplets also change, but they remain on concentric circles. So the rainbow we see is always curved, and what appears in front of our eyes must be a part of an arc of a perfect circle.