How to Predict An Epic Sunrise or Sunset (Tips, Tricks & the must know apps)
“Luck Is What Happens When Preparation Meets Opportunity” – Seneca
Have you ever thought it was going to be a great sunrise or sunset, made the effort to get somewhere to see it only to find a dull sky? I used to do that all the time.
And I’d wonder, how do people get so lucky picking the right ones? Then I found out that it’s not really about luck at all.
Wouldn’t it be great if you could look into a magic ball and it told you exactly what the sunrise would be like? Well, you can! In a way…
Why are sunrises colourful anyway?
Duane Hamacher, a Monash University astronomer, explains the sky’s colour as a result of Rayleigh Scattering. Essentially, when light (from the sun) passes through Earth’s atmosphere, it is scattered by atmospheric molecules. Sunlight is actually ‘light’ from the whole spectrum of colours, however for the purpose of ease, we can view it as blue and red hues. Blue light is scattered more than red light as it has a shorter wavelength, meaning there are more opportunities for it to ‘collide’ with atmospheric molecules.
During the day, sunlight travels a shorter distance (through the atmosphere). This means that over a short distance, blue light is scattered a lot so that we see the sky as blue. This is why the sky appears blue on a clear day.
At sunrise or sunset, sunlight has a much longer distance to travel. This means that sunlight is scattered over a longer distance. Since red light is scattered at a lower rate than blue light, red light is more prominent. This is why red hues light up the sky at sunrise and sunset.
Sometimes, there will be purple hues at sunrise or sunset. This is because there is still enough blue light, which combines with vivid red to produce purple.
An example of the Rayleigh scattering effect
It’s all about clouds and light.
“To produce a vivid sunset, clouds must be high enough to intercept ‘unadulterated’ sunlight… i.e. light that has not suffered attenuation and/or colour loss by passing through the atmospheric boundary layer.” – Stephe F. Corfidi
Essentially, clouds are a great way to predict the colour vibrancy of a sunrise. Clouds that are high in the sky will produce a better, more vibrant sunrise or sunset since they intercept more vivid sunlight. (Thomas Heaton) Low clouds block light and will produce a more dull sky. Clouds at medium height are less predictable and may have a positive or negative impact on colour and vibrancy, depending on other weather conditions.
A cloudless gap at the horizon will generally produce a better sunrise or sunset, as this allows better passage of light since there are no (or few) low clouds.
Thin, broken clouds produce a wider array of textures and colours as the light passes through, especially when there is a variety of cloud formations. (David Peterson) Cloud cover between 30-70% is ideal, as it provides a window of oppurtunity for light to shine through. (Gregory Dunbar) If cloud cover is low, i.e. less than 30%, there isn’t any oppurtunity for red wavelengths to be intercepted. If cloud cover is too high, e.g. greater than 70%, light cannot pass through.
So how can we predict the clouds?
I use a few resources to help me predict what a sunrise or sunset will be like. Here they are:
Cloud Free Night
The first website I use is Cloud Free Night. It’s powered by an Australian & New Zealand astronomy community and is pretty accurate as a result.
The features I use most are Meteogram and Map. Meteogram is a breakdown of total rain and cloud cover forecasts for the next 2 days. The breakdown is incredibly detailed and includes 3 hourly intervals, so you can clearly see if the weather is going to rain on your parade… or your camera.
Map is the next feature I use. I generally view the ‘Total Cloud Cover’ option as it shows an entire range of cloud cover with several days forecasting. Keep an eye out for the middle & high cloud combo – If you see middle & high without any low you’re in for some luck!
Note: To use the website, make sure you visit the sidebar menu (displayed underneath the map in mobile) to select your region.
Bureau of Meteorology (Australia)
The next website is the Bureau of Meterology satellite website. It shows footage on loop from the previous 5 hours. The footage is high resolution, directly from their new Himawari-8 satellite. It’s useful to see cloud formation, coverage and direction in real time.
A note about predicting the future…
For all weather resources, it’s helpful to check them a day or two away from when you’re planning to go out and shoot & if you’re a fanatic like me check when you get up and just before you go to bed. Forecasts are never absolute and as you probably know all too well, they often change.
It’s not just clouds! A variety of other factors affect a sunrise or sunset such as humidity, storm fronts, rainfall, wind direction and speed and atmospheric pollution. In general, less humidity will produce a clearer sunrise with more distinct features. Perhaps surprisingly, higher pollution levels may cause a more vivid sky with bright, vibrant colours, since pollution provides more atmospheric molecules for light to scatter.
Rainfall before or after maybe enhance a sunrise or sunset, but rainfall during one or closely before will likely produce a dismal sky. Likewise, a sunrise before a storm front or a sunset after a storm front has cleared may produce a spectacular sky, with vibrant colours. However, a storm front near or during a sunrise or sunset will likely produce the opposite!
The Main Points:
• Keep an eye out for high clouds
• Aim for cloud coverage between 30-70%
• Look for a range of cloud formations, especially thin, broken clouds
• Shoot a sunrise before a storm front has occurred and sunset after a storm front has cleared
• Use resources like forecasting websites & apps to help predict clouds and weather conditions