We can feel heat, but can we see it? How do we shoot a landscape that conveys temperature? A simplistic solution might be to include a blue sky - after all it is always warm when it is ‘sunny’. However, as we all know, there are many occasions when it can be bitterly cold even when the sky is blue so, clearly, that isn’t the answer. Yet, as we travel insulated in our cars, we can often sense when it is warm outside. How, you might ask?
A Heat Haze
The answer of course is simple - any reasonably perceptive person can see heat, most noticeably as a heat haze. This is an effect of the sun that makes it difficult to see distant objects clearly. It is a strangely beautiful visual phenomenon that creates a unique quivering distortion. Areas in the distance can look strangely liquid, which is why people who have been trapped in a baking desert report seeing a lake of water in the distance; as they moved towards it, it appear to move away. This is a classic mirage.
A mirage is not a result of hallucinations - it is a genuine optical phenomenon. Cold air is denser than warm air and has a greater reflective index. As the light rays travel near the ground surface they are bent upwards towards the colder air, thus creating the distortions. One only ever sees this effect just above the surface of the ground. It tends to be more visible where the ground is flat. Light from the sky is refracted, making appear as if the sky is reflected on the ground and our minds interpret this as water, hence the illusion.
Heat hazes are much more apparent on roads, particularly in the distance. The heat can build up quite noticeably on tarmac which why we tend to see heat hazes above it. The effect can be particularly interesting if you can see a distant vehicle, as it will look as if it is travelling in mid-air. A line of posts can also appear strangely distorted; because the build up of heat is more apparent nearer the surface of the ground, the distortions are much more apparent at the base of the posts. While you can capture the effects of a heat haze with most lenses, as it is relatively distant a telephoto lens works best.
The appearance of some landscapes can also suggest heat
Certainly images of large sand dunes under a deep blue sky could suggest warmth, although you do not need to be quite so obvious. Any terrain devoid of vegetation which appears dry and baked will also suggest heat. This will be particularly apparent if all available moisture has been evaporated. Areas revealing cracked dry earth, as if the land has been scorched by a baking sun, can certainly evoke a sense of warmth.
In the same way as a blue landscape can suggest cold, any landscape bathed in a rich red and orange light will appear warm, as red and orange are classed as ‘warm colours’.
Text and illustrations are from Photographing landscape whatever the weather by Tony Worobiec. Published by RHE Media.