Panoramic IrelandPhotography • Travel • Experiences
A sweeping panoramic, aerial view of a spectacular double rainbow arching over a vast Irish landscape. The primary rainbow is bright and forms a complete, perfect arc, with a fainter secondary rainbow visible above it. Beneath the rainbows, the land is a vibrant patchwork of bright green fields, dotted with small houses, trees, and stone walls. To the left, a large, dark body of water, likely a lough or wide river, reflects the sky. The weather is dramatic: dark, heavy storm clouds frame the scene on both sides, while a patch of bright blue sky with white clouds shines through directly under the rainbow's peak, indicating the sun is breaking through. Image by Panoramic Ireland.

Guide

Double Rainbow Over the Lush Green Fields of the West of Ireland on a Stormy Autumn Day

A lot of photographers who visit Ireland and book a Panoramic Ireland photography tour to spend time with me in Dublin, Galway, or Antrim are surprised by how good the weather can be on this small Atlantic island.

Darren McLoughlinUpdated

Many myths abound about rain and dark, dank weather, but Ireland sees plenty of sunshine. And stormy days often hand you one of the most spectacular things the sky can do: a rainbow, and on a good day, a double.

Sunshine in Ireland

Ireland sees between 1,100 and 1,600 sunshine hours per year, similar to England, Wales, Scotland, Iceland, and Norway. See more from Met Éireann: Sunshine and Solar Radiation.

You only need moments of sunshine to capture a rainbow. Here, during a break in the cloud and squally rain, a double rainbow arcs above the green, field-filled landscape of the west of Ireland and the stormy lake.

Why Ireland is so good for rainbows

A rainbow needs two things: rain in front of you and the sun behind you, low enough in the sky. Atlantic weather supplies both. Showers move through fast, and the cloud breaks behind them.

The sun must be lower than about 42° above the horizon. At Ireland’s latitude, the midsummer midday sun climbs to roughly 60°, so you won’t see a rainbow at noon in June. In autumn and winter the sun never gets that high, so a rainbow is possible at any hour of the day. October and November are prime rainbow months.

Anatomy of a double rainbow

  • Primary bow: Sunlight enters a raindrop, refracts, reflects once off the back of the drop, and refracts again on the way out. Each colour bends by a slightly different amount (dispersion), which spreads white light into a spectrum. Red leaves at about 42° from the antisolar point and violet at about 40°, so red is on the outside of the arc.
  • Secondary bow: Some light reflects twice inside the drop before exiting. It emerges at roughly 50° to 53°, so the secondary bow sits outside the primary. The extra reflection reverses the colour order, with red on the inside and violet on the outside. It’s also noticeably fainter, because each reflection loses light.
  • Alexander’s band: The dark strip of sky between the two bows, clearly seen in the image above. Raindrops send no light back at those angles, so the sky looks darker than the sky around it. It’s named after Alexander of Aphrodisias, who described it around AD 200.
  • Supernumerary bows: Faint pink and green bands tucked just inside the primary bow. They come from the wave nature of light (interference), and they show up when the raindrops are small and similar in size.
  • Antisolar point: The point in the sky directly opposite the sun, which you can think of as the shadow of your own head. Every rainbow is part of a circle centred on it. The horizon cuts off the lower part, so you normally see an arc. Strictly speaking, every observer sees their own rainbow, formed by different drops.
  • Twinned rainbow: Often mistaken for a double. A twinned bow is two primary bows that share a base, caused by raindrops of two different sizes. A true double rainbow has the reverse colour order in the outer bow, plus Alexander’s band between.
  • Higher-order bows: Tertiary and quaternary bows exist, but they form on the sun’s side of the sky and are very faint, so they’re rarely seen.

The old explanation of the rainbow’s geometry goes back to Descartes in 1637, and the seven-colour spectrum (red, orange, yellow, green, blue, indigo, violet) comes from Newton. In Irish, a rainbow is a tuar ceatha.

Photographing a double rainbow

  • Go wide. A primary bow spans about 84° across, and the secondary about 100°. To fit both bows in a single frame you need an ultra-wide lens, or a stitched panorama.
  • Use a polariser. Rainbow light is strongly polarised. Rotate a circular polariser and watch the bow strengthen or fade, then stop at the strongest point.
  • Expose for the sky. Watch your highlights. A slightly darker exposure makes the colours more saturated and Alexander’s band more obvious.
  • Be quick. Squall-driven rainbows can last only minutes. Know where the light is going, then be ready.

More Rainbow Scenes from Ireland

Join Me in Any Season

Don’t believe the myths. Embrace the changeable weather and fantastic scenery, and join me through autumn, winter, and spring to photograph landscapes, seascapes, and urban scenes in Ireland.

The photograph featured in this article is available for editorial and commercial licensing.

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