Pilots do see rainbows when they are flying, but the conditions have to be just right. Rainbows form when sunlight interacts with water droplets in the atmosphere, creating the colorful prism effect. For pilots to see rainbows from their aircraft, there needs to be moisture in the atmosphere and the sun needs to be at around a 40 degree angle from their perspective. The droplets also need to be at the right distance and angle from the light source and observer.
What causes rainbows and how do they form?
Rainbows are optical phenomena that occur due to the reflection, refraction and dispersion of sunlight by water droplets in the atmosphere. Here is a quick overview of how rainbows form:
- Sunlight enters the raindrop and slows down as it travels from air to denser water.
- The light refracts (bends) as it enters the water droplet, separating it into its different wavelengths (colors).
- The light reflects off the inside back wall of the raindrop.
- As the light exits again into the air, the wavelengths refract and disperse at different angles, creating the rainbow spectrum we see.
The most vivid and bright rainbows form when the raindrops are smaller and more uniformly sized. Each individual raindrop acts like a tiny prism separating and refracting the white light from the sun into its component colors. Together, the vast number of raindrops creates the rainbow.
Optimal conditions for rainbows
For a pilot to see a rainbow from their aircraft, certain conditions need to occur:
- Rainfall or moisture in the atmosphere. Raindrops or other water droplets are needed to disperse and refract the light.
- Sunshine from behind the observer. The sun needs to be able to shine into the raindrops. Usually this means the sun behind the observer at around a 40 degree angle from their perspective.
- Correct angle of sunlight refracting through the water droplets. Around 42 degrees is optimal for the most vivid rainbows.
- Appropriate distance between the water droplets, observer, and light source. Typically the droplets need to be about 42-51 degrees in angular radius from the observer’s perspective.
Essentially sunlight needs to be refracted by water droplets at the necessary angle to the observer’s eyes for a rainbow to be visible. That’s why on the ground we normally see rainbows in the opposite direction from the sun in the rain when it’s still fairly bright and sunny.
Why pilots can see rainbows while flying
During their flights, pilots have a greater chance of meeting the optimal conditions for spotting rainbows. Here’s why pilots are likely able to see rainbows from the cockpit:
- Altitude – From the altitude in the sky, pilots are more likely to view rain showers from above and see the sun shining through them at the required 42 degree angle or more.
- Perspective – The viewing angle from the cockpit allows the sun, raindrops, and their eyes to often be at the perfect orientation for rainbow spotting.
- Weather conditions – Airplanes fly above rain showers and storms, allowing the possibility of seeing sun and rain interacting.
- Time in the air – Pilots spend extended periods of the day flying which gives more opportunity for rainbow optimal conditions to occur.
So while we are limited to rainbow sightings on the ground when the conditions are right, pilots have the advantage of height, perspective, and time in the air to frequently see rainbows from above during their flights.
Where pilots are most likely to see rainbows
Certain geographical locations and weather situations are more prone to rainbow spotting by pilots:
- Tropical regions – Areas like Hawaii experience frequent rain showers with sunshine ideal for rainbows.
- Coastlines – The interaction of land and ocean can result in rain while remaining sunny.
- Thunderstorms – Rain and sun often occur simultaneously around the edges of storms.
- Morning flights – Sun angles tend to be lower early in the day, meeting rainbow requirements.
- Descents – As aircraft descend, angles shift favorably for spotting rainbows below.
So tropical environments, coastal areas, the peripheries of heavy weather, and times of optimal sun angles tend to lend themselves to more rainbow observations by pilots.
Flying through rainbows
It’s not just a myth that you can fly through a rainbow – pilots do frequently pass right through the multicolored arcs. However, the rainbow visual effect does not actually surround the aircraft like a physical object. As the pilot’s perspective and angle to the sun shifts, the apparent position of the rainbow will change relative to the airplane. Once inside the rainbow, its colors will disappear since the viewing angle no longer supports the conditions needed to see it. The rainbow only exists optically from certain perspectives when light is refracted from specific raindrops.
Double rainbows
Sometimes pilots will spot double rainbows from the cockpit. This occurs when sunlight reflects twice inside raindrops, creating a secondary, dimmer rainbow above the main one. The conditions have to be very optimal for the second reflection to happen, so double rainbows are more rare. But pilots do occasionally see this phenomenon when the alignment is just right.
Rainbows around the world
Here are some of the most common places in the world for pilots to witness rainbows from the air:
Hawaii
Frequent rain combined with abundant sunshine makes Hawaii a prime rainbow viewing location, with pilots likely seeing them regularly on flights in the islands.
Caribbean
The tropical climate of the Caribbean islands lends itself to rainbow creation. Pilots report seeing rainbows regularly when flying in this region.
British Isles
The interaction of weather systems and sunlight over the British Isles often creates ideal rainbow conditions. Pilots see them on flights over Ireland and Britain.
Southern United States
Storms developing over the southern states often produce vivid rainbows visible to pilots during take-off and landing or in passing flight.
Malaysia
Frequent rain combined with abundant sunshine makes Malaysia a prime rainbow viewing location, with pilots likely seeing them regularly on flights.
Coastal Peru
The intersection of moisture, mountains, and sunlight along the Peruvian coastline leads to excellent rainbow spotting for pilots.
Switzerland
Fast moving alpine weather systems over Switzerland make rainbow sightings fairly common for pilots traversing the country.
New Zealand
New Zealand’s geography and climate lead to abundant rainbow opportunities. Pilots see them regularly around coasts and hills.
Central Africa
Passing storms and sunshine over the continental interior often create vivid rainbows for pilots operating in central African nations.
Interesting facts about rainbows
- Rainbows are optical illusions – they are not actually physical objects.
- The colors always appear in the same order – red, orange, yellow, green, blue, indigo, violet.
- A rainbow at night – often called a ‘moonbow’ – is caused by reflected light from the moon rather than the sun.
- Double rainbows have their color order inverted in the secondary arc.
- It’s impossible for someone to see a complete circular rainbow. The farthest is a semicircle of around 84 degrees.
- Alexander’s band – the dark area between rainbows in a double rainbow – is caused by destructive interference.
- Rainbows are most commonly seen in the early morning and late afternoon when sun angles are best.
- Sprites and air glow phenomena sometimes occur above rainbows during thunderstorms.
- The world record for the longest lasting rainbow was in Wetherby, UK at 6 hours.
- Up to 5 separate rainbows can be observed if conditions are extremely ideal, though this is very rare.
Rainbows in aviation history
Rainbows have played a role in famous events in aviation history. Here are some notable moments:
Amelia Earhart – January 11th, 1935
Pioneering aviator Amelia Earhart became the first person to fly solo from Hawaii to California. She encountered heavy storms during her flight before seeing a rainbow, which signaled improving conditions to proceed and complete the historic trip.
First transpolar flight – June 18th, 1937
A Soviet crew piloting an ANT-25 aircraft completed the first transpolar flight from Moscow over the North Pole to Vancouver, Washington. As they crossed Alaska, they spotted a vivid rainbow, marking their proximity to their destination.
Space Shuttle Challenger disaster – January 28th, 1986
Prior to the tragic Space Shuttle Challenger explosion, numerous eyewitnesses saw a brilliant rainbow in the sky above the launch site, a possible ominous warning sign in retrospect.
Hawaiian Airlines Flight 3 – April 28th, 1988
The pilots of a Hawaiian Airlines flight saw a rare triple rainbow phenomenon near Hilo prior to the failure of their aircraft’s engines and successful gliding landing.
Los Angeles “rainbow palm” phenomenon – October 13th, 2009
A unique “rainbow palm” was observed over the palms of Los Angeles during a rainstorm. Pilots saw the rainbow effect intersecting the palm trees at unusual angles.
Delta Airlines rainbow contrail – August 8th, 2014
A Delta Airlines flight from San Francisco produced a contrail during ascent that generated a circumhorizontal rainbow effect visible across California.
Seeing rainbows from commercial airline flights
Passengers aboard commercial airline flights also occasionally get to witness rainbows from cruising altitude. While less common than for pilots who fly frequently, here are some instances where rainbows may be observable by passengers:
- During take-off or landing as the aircraft is at lower altitudes.
- While flying at lower cruising altitudes in poor visibility requiring less height.
- When ascending or descending through optimal rainbow viewing angles.
- Passing through colorful contrails left by other planes.
- Over areas prone to frequent storms and sun like coastal environments.
- Shortly after takeoff or before landing over rain occurring close to the airport.
So while not a guarantee, passengers do have opportunities to catch glimpses of rainbows from commercial flights under the right conditions.
Why rainbows are significant for pilots
Spotting a rainbow holds significance for pilots beyond just a visual treat. Rainbows can provide useful information to pilots when encountered in flight:
- Sign of improving weather – After storms, rainbows indicate clearing and showers dissipating.
- Position indicator – Relative position of a rainbow can indicate an aircraft’s location.
- Aid navigation – Rainbows help pilots orient themselves spatially in the air.
- Altitude indicator – Angle and size of observed rainbows give altitude clues.
- Visibility marker – Presence of a rainbow means visibility conditions are good.
So rainbow sightings are more than just momentary phenomena to enjoy. They also serve as useful markers for pilots navigating through changing weather and atmospheric conditions.
| Type of Rainbow | Cause | Rarity |
|---|---|---|
| Primary rainbow | Single internal reflection of light in raindrops | Common |
| Double rainbow | Second reflection of light in raindrops | Less common |
| Full circle rainbow | Observer has sun directly behind them | Very rare |
| Rainbow with supernumerary arcs | Smaller and more uniform water droplets | Uncommon |
| Twinned rainbow | Combination of main and secondary bows | Rare |
Conclusion
In summary, pilots do frequently see rainbows from the vantage point of the cockpit when the conditions align for sunlight to refract through raindrops at the ideal 42 degree angle. Rainbow spotting is more common for pilots than people on the ground since aircraft altitude, perspective, weather, and time in the air lends itself to rainbow formation. For pilots, rainbows can serve as useful indicators of weather changes and location clues rather than just visual splendor. So next time you fly through stormy skies, listen for the pilots chattering excitedly about any rainbows coming into view!