Scientists Say: Gradient | Science News for Students

Scientists Say: Gradient

This is the rate that something — such as elevation, concentration or temperature — changes over a distance or time
Oct 23, 2017 — 6:30 am EST
bee on flower
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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Power Words

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air pressure     The force exerted by the weight of air molecules.

elevation     The height or altitude at which something exists.

gradient     From the word “grade,” it describes the incline, slope or degree of increase in some measure (such as temperature, pressure or even color) that develops as one moves in time, position or along some scale.

molecule     An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).

pollinator     Something that carries pollen, a plant’s male reproductive cells, to the female parts of a flower, allowing fertilization. Many pollinators are insects such as bees.

pressure     Force applied uniformly over a surface, measured as force per unit of area.

sea     An ocean (or region that is part of an ocean). Unlike lakes and streams, seawater — or ocean water — is salty.

sea level     The overall level of the ocean over the entire globe when all tides and other short-term changes are averaged out.