Geometry in Nature: Concentric Circles
Try dropping a pebble in some water and notice the ripples! You have just created concentric circles. There are many examples of concentric circles in Nature.
Concentric circles all share the same centre but have different radii (distance from the circle centre to its outer edge) so they fit inside each other. The space between two concentric circles is call the annulus.
A common example is the ripples when a stone hits the surface of water. The stone introduces energy to the system and pushes the water out of the way to form ripples.
Did you know these ripples are also called Capillary Waves which travel along the phase boundary of a fluid (e.g. water) and are dominated by the effects of surface tension (how strongly molecules in a liquid stick together). Water has a high surface tension which explains why is can form droplets and how some insects like water boatmen can “walk on water”.
Other examples of concentric circles include layers of an onion and tree rings. Concentric circles can also be found in geology when the build-up of mineral precipitate can form as successive concentric layers around a central core.
Did you know the science of tree rings is called Dendrochronology. As trees grow, they make rings of different widths and colours. Variation between rings occurs due to changing seasons and environmental conditions overtime. Scientists can use tree rings as a dating tool and gather information about past climates. This is called Dendroclimatology.
How many examples of concentric circles can you find?
