Can you tell if it is sunrise or sunset?

Ankita Anirban has helped us paint the picture of an answer to this question from Manik. It was over to painter and creator of the series Dinotopia, James Gurney, and physicist William Livingston to shed light on the situation...

Ankita - First we put it to the forum, and got your suggestions. Evan_au suggests looking at the time stamp on your photo - which I think is cheating! ChiralSPO recommends looking for known landmarks, but that methods relies on you already knowing something about the landscape. We turned to James Gurney, painter and creator of the series Dinotopia, to ask him for his thoughts on this.

James - There's nothing fundamentally different about the light effects at sunset or sunrise, and there's no way to tell which you're looking at from the light and colour effects alone. The cause of those light effects are the same. Sunlight travels through more atmosphere as the rays approach the horizontal. Passing through more air scatters out more blue wavelengths from the light rays, making the light that remains appear increasingly orange or red. Of course, this effect happens both at sunrise and at sunset when colours are at their richest.

A single photo or a painting may be able to tell you about the altitude, the cardinal direction of the Sun, and about the height and distribution of cloud layers. And some art historians have argued that paintings of sunsets after the eruption of Krakatoa in 1883 reveal colours that were more pronounced worldwide. But it can't tell you whether it's morning or evening.

Ankita - If there are differences between sunrise and sunset, they're qualitative and subjective. In some environments, humidity and dust may be stirred up at the end of the day because of evaporation and turbulence, and these effects can increase the saturation of the colours. But you wouldn't be able to guess that from a single image.

James - Emotional subjectivity also plays a part in our human perception of sunsets and sunrises as we experience them in time. While a sunset builds gradually to a dramatic crescendo before quickly transitioning to twilight, a sunrise starts off with a blast of colour and, as Wordsworth says, the "vision splendid" fades "into the light of common day".  

Ankita - What about the Moon? Can you tell whether it’s moonrise or moonset from a picture? William Livingston, from the National Solar Observatory in the USA, wrote in to tell us this:

“In the case of the Moon, every society has a favourite imagined figure marking the full Moon. In the Orient and Europe it is a hare. To North Americans, it is “the Lady in the Moon”. At Moonrise, she is seen in profile, looking downward. At Moonset, her gaze is upward”.

Next week, we’ll be answering a question from Saugatt...

Saugatt - Hi, Chris, this is Saugatt from Nepal, and my question is - because of the monsoon, the death toll raised to around 150 in India, Nepal, Pakistan and Bangladesh. What is the exact cause of monsoon rain, and how will it be affected because of global warming?"