Let’s learn about rivers

aquatic: An adjective that refers to water.

chemical: A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H₂O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

climate: The weather conditions that typically exist in one area, in general, or over a long period.

climate change: Long-term, significant change in the climate of Earth. It can happen naturally or in response to human activities, including the burning of fossil fuels and clearing of forests.

cloud: A plume of molecules or particles, such as water droplets, that move under the action of an outside force, such as wind, radiation or water currents. (in atmospheric science) A mass of airborne water droplets and ice crystals that travel as a plume, usually high in Earth’s atmosphere. Its movement is driven by winds. 

continent: (in geology) The huge land masses that sit upon tectonic plates. In modern times, there are six established geologic continents: North America, South America, Eurasia, Africa, Australia and Antarctica. In 2017, scientists also made the case for yet another: Zealandia.

crop: (in agriculture) A type of plant grown intentionally grown and nurtured by farmers, such as corn, coffee or tomatoes. Or the term could apply to the part of the plant harvested and sold by farmers. (in zoology) A throat-like structure that can store food as an animal, especially a bird, moves from the field back to its nest.

delta: The fourth letter of the Greek alphabet. (in geology) Land that forms in the mouth of a river as silt that had been carried in the water settles out as currents slow when the river meets a larger body of water. Deltas allow the water to fan out in new channels, and sometimes to create wetlands for waterbirds and other animals.

ecosystem: A group of interacting living organisms — including microorganisms, plants and animals — and their physical environment within a particular climate. Examples include tropical reefs, rainforests, alpine meadows and polar tundra. The term can also be applied to elements that make up some artificial environment, such as a company, classroom or the internet.

electricity: A flow of charge, usually from the movement of negatively charged particles, called electrons.

evaporate: To turn from liquid into vapor.

Grand Canyon: A natural canyon in northwest Arizona that formed as the Colorado River cut through the rock here over the past 5 million to 6 million years. This is one of many canyons on the river, which drains water from seven states. The Grand Canyon is 446 kilometers (277 miles) long. Its depth varies. At its deepest point, the river is 1,829 vertical meters (6,000 feet) below the upper rim. From rim to rim, the canyon’s width also varies — from about 16 kilometers (10 miles) to 29 kilometers. Of this impressive national land formation, more than a million acres (4,931 square kilometers, to be exact) was turned into a U.S. national park in 1919.

groundwater: Water that is held underground in the soil or in pores and crevices in rock.

meltwater: The water that comes from melting ice. The quantities can be large and show up quickly when it comes from melting glaciers, ice sheets and snow-capped mountains.

moisture: Small amounts of water present in the air, as vapor. It can also be present as a liquid, such as water droplets condensed on the inside of a window, or dampness present in clothing or soil.

pesticide: A chemical or mix of compounds used to kill insects, rodents or other organisms harmful to cultivated plants, pets or livestock; or unwanted organisms that infest homes, offices, farm buildings and other protected structures.

pollutant: A substance that taints something — such as the air, water, our bodies or products. Some pollutants are chemicals, such as pesticides. Others may be radiation, including excess heat or light. Even weeds and other invasive species can be considered a type of biological pollution.

precipitation: (in chemistry) The creation of a solid from a solution. This can occur if there is too much of a chemical to dissolve completely into a solution. It also can be a sign that some chemical reaction is taking place. (in meteorology) A term for water falling from the sky. It can be in any form, from rain and sleet to snow or hail.

runoff: The rainwater that runs off of land into rivers, lakes and the seas. As that water travels through soils, it picks up bits of dirt and chemicals that it will later deposit as pollutants in streams, lakes and seas.

seawater: The salty water found in oceans.

sediment: Material (such as stones and sand) deposited by water, wind or glaciers.

species: A group of similar organisms capable of producing offspring that can survive and reproduce.

taint: To contaminate something with an unexpected, unnatural or illegal substance.

terrain: The land in a particular area and whatever covers it. The term might refer to anything from a smooth, flat and dry landscape to a mountainous region covered with boulders, bogs and forest cover.

tool: An object that a person or other animal makes or obtains and then uses to carry out some purpose such as reaching food, defending itself or grooming.

wastewater: Any water that has been used for some purpose (such as cleaning) and no longer is clean or safe enough for use without some type of treatment. Examples include the water that goes down the kitchen sink or bathtub or water that has been used in manufacturing some product, such as a dyed fabric.