Scientists Say: Gradient

This is the rate that something — such as elevation, concentration or temperature — changes over a distance or time


Bees follow a gradient of scent molecules to find flowers. A strong scent means they are getting closer.

wael alreweie/istockphoto

Gradient (noun, “GRAY-dee-ent”)

This is the rate at which something changes over a distance or time. Temperature may change over distance, for example. Air pressure could, as well. For example, there is air pressure is higher at sea level. The farther up you go in elevation, the lower air pressure gets. The rate of that change is a gradient.

Gradients can also be the rate that something changes over time. For example, if a smell gets stronger over time — because the number of odor molecules are increasing — the rate it increases can be described as a gradient.

In a sentence

Pollinators such as bees follow a gradient of scent molecules to find flowers; a stronger scent means a meal is near!

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Bethany Brookshire was a longtime staff writer at Science News Explores and is the author of the book Pests: How Humans Create Animal Villains. She has a Ph.D. in physiology and pharmacology and likes to write about neuroscience, biology, climate and more. She thinks Porgs are an invasive species.

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