Lunar Rainbow - Victoria Falls
A Wonderful Sight Not To Be Missed......
Each full moon the Victoria Falls rainforest re-opens in the evening for special tours to witness the magic of the lunar rainbow -weather and spray permitting!
Victoria Falls is one of the few places on earth where this natural phenomenon occurs and where it can be witnessed with ease. Yet many people visit here without knowing of this natural phenomenon, but it is one of the most impressive sights of Victoria Falls.
What is a lunar rainbow?
Just like its day-time equivalent, the lunar rainbow or ‘moonbow’ is created as light is refracted through water particles in the air, but instead of the light source being the sun it is now the moon.
Lunar rainbows are much fainter than their day-time forms with which we are all so familiar. This is because of the lower amount of light reflected from the surface of the moon. Only when the moon is full and skies clear of cloud is enough light reflected to create a moonbow, which always occur in the sky opposite from the moon in relation to the observer.
The human eye finds it difficult to discern the colours in a moonbow because the light is usually too faint from the moon to excite the human eye cone colour receptors (this is true of all night-time vision). Hence, moonbows can appear to some human eyes to be washed-out and white, without the concentrated colours of a day-time rainbow.
This varies according to the quality of the individuals night vision and the number and responsiveness of colour sensitive cones present in the retina of their eyes. So for some people it can be a bit disappointing, if your expectations of a bright rainbow are too high. My response to that is; seeing a seventh wonder of the world, by magical moonlight is a surreal experience in itself. It is NOT just about the moonbow.
The vibrant colours of a lunar rainbow do show very clearly in photographs with a long exposure. So for the avid photographer this is particularly exciting and challenging. See my tips below.
When is the best time of year to see a lunar rainbow?
This comes down to a combination of factors. 1) Sufficient rising-spray to refract the moonlight. 2) Not too much spray to obliterate the background (the waterfall) or the moonlight 3) A full moon, including the night before and after -3 nights only per month 4) Clear skies, so the moonlight is not diffused by clouds.
The optimal months for these factors to occur together, on both the Zimbabwean and Zambian side, is June, July and August. That is not to say you won't see the lunar rainbow outside of these months, just that these are the best.
Read on to find out about the other months...
February and early March have the right water levels but have higher a chance of cloud cover and the tour being cancelled. No moonlight means no lunar rainbow. This unfortunately, is just luck of the draw but the months of December, January, February and March are the main rainy season, so there is more likelihood of cloud cover. The months of May, June, July and August are the winter months with clear skies on the whole.
The Victoria Falls high water flow months are March through till early June, with peak flow around April and May. In these months there is a terrific amount of rising-spray, which is great for big and strong moonbows, but with so much spray it tends to obliterate the background somewhat. This might be more pertinent to the photographer than it is to the casual observer. The high rising cloud of spray can also block out the moonlight, depending on the wind direction.
No spray from the falls means no lunar rainbow, so in the dry season months of September, October, November and early December, it is only possible to see the moonbow from certain viewpoints but not all.
As the Zambian side almost completely dries up during these months, it is not visible from that side and in fact, the tours are closed (the exact dates vary year to year, dependant on water levels).
On the Zimbabwean side, the moonbows are still visible during these dry months, as there is still sufficient spray but the moonbows will not be as strong or as big and are only visible from a couple of viewpoints.
What is the best time of night to see a lunar rainbow?
This spectacle is best witnessed in the hours soon after moonrise before the moon gets too high. The rainforest opens during these optimal hours and the times are detailed below for both winter and summer.
The rainforest only opens for lunar rainbow tours on 3 nights; the night before, the night of and the night after the Full Moon (see chart below for dates). This is when the moon is at its brightest and the chances of seeing a moonbow are greatest.
What are the best viewpoints to see the lunar rainbow?
The waterfall runs in an approximate east-west direction. The moon rises in the east and sets in the west, varying northwards and southwards moderately throughout the year. To see a lunar rainbow you need the moon to be behind you. So in the hours after the moon rises, you will need to be looking in a westerly direction.
Due to the physical layout of the waterfall and the width of the gorge in places, the absolute best viewpoints are in Zambia along the eastern cataract, but only in the months detailed above, in the "best time of the year" section.
On the Zimbabwean side, you can also see a fantastic lunar rainbow but you are a more limited, due to the width of the gorge in places. The best viewpoint is at number seven, looking into Devils cataract.
What to take with you and what to wear.
The moonlight is bright enough for you to find your way around but it is still advisable to take a good torch. However, please be aware of others and don't shine this around too much as it can affect their photographs.
Generally in the evenings the wind dies down, which means that the spray rises straight up, so you don't get as wet as during the day. But it is still a very good idea to take a raincoat and/or an umbrella to keep dry against the variable spray. Comfortable shoes with good grip are essential, as the paths can get slippery and we don't want any accidents at night.
During the winter months you will definitely need a warm jacket. In the summer months, as long as you keep dry you shouldn't need anything.
Camera and tripod if you want to get decent photos - read my essential tips on taking photographs below.
How much does a lunar rainbow tour cost?
Please visit our Victoria Falls entrance fee page which has up-to-date park entrance fees for both the Zimbabwean and Zambian sides. In addition to these fees, if you decide to go on a guided tour, which will include transfers from your hotel, you will pay an addition $20 to $25.
Can I take the lunar rainbow tour on my own?
Entering the rainforest at night is slightly different from during the day. During the day you can enter at what time you like and wander around for how long you like without a guide. At night the gate opens at a specific time (see below) and everyone enters at that time, then gathers inside the gate.
After a short brief from the parks ranger he leads the way, with another ranger at the rear. The parks rangers encourage you to stay in a tight group, but with bigger groups this is not a reality and everyone tends to split up. The tour lasts one hour.
You will need to make your own way down to the rainforest entrance by taxi. Don't walk there at night due to the presence of elephant and buffalo and make sure you are there about 15 minutes before the tour is specified to start. Pay your park entrance fees and enter the gate as stated above and wait for the ranger to start. Then wander around the rainforest with the ranger, but he won't impart much information.
A guided tour includes pick-up and drop-off from your hotel. Your guide will take you through the entrance gate, as you will have already paid your park fees and then gather together on the inside (as on the self-guided tour). The parks ranger will lead the whole group but you will have your own guide to show you around and impart lots of information on the Victoria Falls.
How do I take good photographs of a lunar rainbow?
Getting good photographs of a moonbow is not that easy and requires a little bit of photographic knowledge, a camera that you can adjust to manual settings and without question, a tripod.
Due to the low light conditions just using a cell phone is unlikely to produce results that you will be happy with and when you look at the photograph there may be no moonbow in it at all.
The tour only lasts one hour, so time is tight for photographers to set up and get what they want. So don't waste too much time at viewpoints which don't have clear moonbows.
Flashes of any kind will kill the picture.
So on cameras with manual settings, first you need to mount it on a sturdy tripod, then you need to crank up the ISO to around 800 to 1000. Set the aperture to the fastest your lens allows (about 2.4) and then experiment with shutter speeds, but 8 to 15 seconds seems to works well. This will give you brighter rainbows than you can see with the naked eye and a silky water effect. The photographs will almost appear like daytime, but with stars, as with the photo below.
To avoid camera shake when pressing the shutter button, it's a good idea to use the self-timer setting or use a remote shutter release, if you have one.
The biggest problem you will face is getting your pictures in focus. The camera's autofocus just cannot function in these low light conditions and will keep going in and out of focus. If you are looking through the viewfinder or on the back screen it's too dark to actually get a focus point. My suggestion is to set this up during daylight hours, adjust your camera to manual focus and set it to an optimal distance (just before infinity) then lock it there so it doesn't move.
If you want anything in the foreground highlighted, then shine on it briefly with your torch, while the shutter is open. Bear in mind your depth of field is very shallow here though because of the fast aperture setting.
The spray at night tends to be a lot calmer than during the day, as there is not so much wind but you might still have to wrangle with the spray from time to time at certain spots. An umbrella is very useful here and a dry cloth to keep cleaning your lens of water spots.
If you are lucky enough to be travelling to Victoria Falls during a full moon (see the dates below) we would highly recommend doing this tour.
Is Victoria Falls the only place where you can see a lunar rainbow?
The event of a regularly occurring natural moonbow is not unique to the Victoria Falls. Wallaman Falls (Australia), Yosemite Falls (California, USA), Kihei (Maui, Hawaii, US), Cumberland Falls (Kentucky, USA) are also famed for their moonbows. They used to occur at Niagara Falls, but do not occur any longer because of the surrounding light pollution – a warning to both Zambia and Zimbabwe to control the development of the area surrounding the Victoria Falls.
Moonbows were first known to be mentioned by Aristotle, in his Meteorology, circa 350 BC.
Definitely a wonder of nature – Not To Be Missed…
Dates and times of lunar rainbow viewing at Victoria Falls
Lunar Rainbow Tours Start Times
Below are the summer and winter start times for the tours the day before, the day of, and the day after the full moon:
Moonlight viewing days for the Rainforest 2020
Below are the dates on which the Victoria Falls National Park is open for lunar rainbow tours.
2020 Lunar Events
January 10 - Penumbral Lunar Eclipse (19:07 to 23:12)
Moonlight viewing days for the Rainforest 2021
Below are the dates on which the Victoria Falls National Park is open for lunar rainbow tours.
2021 Lunar Events
April 27 - Super full moon
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