Rainbow Forecaster

Instructions

The appearance of a rainbow depends on several factors, including the sun's height, as well as direct sunlight and rain being present together.

This app gives you two pieces of information:-

1. The first screen tells you the sun's position at the current time. This is for use in the field if you are planning photography when you suspect a rainbow could appear, or if you just want to look for one. If the sun's height is correct for a rainbow (betwwen 0° and 42°), the screen will also show you the rainbow's potential height, and direction. This allows you to plan composition of photos etc.

If your GPS location is not detected, you may need to select it on the map view.
If you do not have an internet conenction, you will also need to set your GMT offset (time zone).

2. The second screen (daily prediction) attempts to pull your local weather data (for a given day) in order to give you a longer range rainbow forecast . It uses weather data to give you an idea of when conditions will be good to look for a rainbow. Ideal conditions occur when the sun is below 42° height, there is some rain but also some sunlight, and when the wind in blowing away from the sun's direction (rainbows tend to appear at the trailing edge of rain storms.) The right-most column gives you an overall forecast rating, ranging from no chance, through 'poor', 'ok', and up to 'optimal'. Optimal conditions occur when there is a forecast for sun and rain close together, and the wind is blowing the right way.

Limitation: The daily prediction screen requires an internet connection and does not currently save its data. This may be addressed in future versions.