Rainbow
Some silly ideas ...
If I stand outside on a sunny afternoon, and use a garden hose to spray a fine mist into the air, I see a full circle rainbow opposite the sun. However, only part of that rainbow is above the horizon, the rest is down near by feet. I imagine the same effect would occur if I stood on the edge of a canyon with the sun behind me and rain falling into the canyon. However, the lower part of the circle is below the horzon, not really "in the sky".
I can move the garden-hose circular rainbow fully into the sky by arranging a large mirror to reflect the sunlight upwards into the water droplets.
I suppose it would also be possible to sail a boat to the middle of a calm lake that is reflecting sunlight upwards into the falling rain. However sunlight reflected by water is relatively dim so the rainbow may be difficult to see.