The Two Rules of Foliage

1. When seen against the skyline, leaves are always darker than the background.

2. When seen below the skyline, leaves in a natural setting are always lighter than their surroundings.

The "skyline" is the line of the top of the trees against the sky. Here's an example of Rule 1, which is not surprising.

The second law may come as a surprise, because we always tend to think of leaves as dark silhouettes, and we tend to paint them that way. But in a natural setting, whenever you see any leaf against any background below the sky, chances are that nearly every single leaf is lighter than what is behind it.

The exceptions to Rule #1 are so rare that they are momentary and breathtaking. Here’s a shot of a Rule 1 exception, taken from a fast-moving car when the late afternoon light penetrated beneath a deck of stormclouds. The effect only lasted five minutes. It can be very exciting to break this rule, but all the conditions should be carefully observed.

The exceptions to Rule #2 (pink circle at right) happen a little more often, but usually only when leaves are seen against human interventions, like lawns, walls, or cleared areas. If you walk around in a forest or a meadow, the leaves are almost always lighter than what’s around them.

I assume that Rule #2 happens because of the light-seeking nature of leaves. They are little machines that are superb at angling for the best position to capture the most light.