A
- Adaptation – A trait or a behaviour of the organism that helps it survive in certain conditions and increases the likelihood of producing offspring
- Air – A mixture of gases that surrounds Earth
- Air pressure – The pressure exerted by air on the ground
- Amphibian – A vertebrate animal that reproduces in water but lives on land as an adult
- Aquatic plants – Plants that have adapted to life in water
- Artificial lake – A man-made lake
- Atmosphere – The layer of air that surrounds Earth
- Atom – The smallest particle of a substance
B
- Bacteria – The smallest single-celled organism
- Baseflow – The low water level that occurs when there is no precipitation or snowmelt and the river feeds mostly on groundwater
- Beach – The terrestrial part of a coast which is occasionally flooded
- Bog – A type of wetland that accumulates peat
- Brackish water – Water that is less saline than seawater but more saline than freshwater
C
- Capillarity – The ability of a liquid to flow against gravity in a narrow space such as a thin tube
- Capillary – A very narrow tubular cavity in a substance
- Carbon dioxide – A gas contained in the air which is used by plants to grow
- Carbon monoxide – A toxic gas that is produced when there is not enough oxygen for proper combustion
- Chlorophyll – A substance that gives plants their green color
- Cirrus clouds – Delicate, hair-like clouds that form at altitudes of 7-10 km
- Climate – The average state of weather over a long period of time
- Cloud – A visible collection of water droplets or ice crystals above the ground, formed by the condensation of water vapour
- Community – A collection of organisms living in an area with a similar environment
- Condensation – The change of a gas into a liquid
- Consumer – An organism that consumes other organisms
- Cumulonimbus clouds – Dense, towering vertical clouds associated with thunder storms and heavy precipitation
- Cumulus clouds – Puffy cotton-like clouds that form at altitudes of 2-6 km
D
- Decomposer – An organism that feeds on dead organisms
- Decomposition – The process of breaking the complex substances down into more simple particles
- Delta – A river mouth where the mainstem branches into several distributaries
- Depression – An area that is lower than the surroundings, which may have a lake at the bottom
- Dew – The tiny water droplets formed on the ground by the contact of moist air with the cooled ground
- Distributary – A river branch flowing away from the mainstem
- Drainage basin – The area from which the water that flows into a common body of water comes from, bordered by a drainage divide
- Drainage divide – An elevated area that separates the neighbouring drainage basins
- Drinking water – Water that is suitable for drinking
E
- Echolocation – A technique used by some animals to determine the location of objects using reflected sound
- Emergent plant – An aquatic plant that is rooted in the ground with its stems, flowers, and leaves rising above the water
- Environmental toxins – Substances from human activity that are harmful to living organisms, accumulate in the upper links of the food chain and act slowly
- Eutrophic lake – A lake that has a lot of nutrients and can support an abundance of vegetation
- Evaporation – The change of a liquid into a gas
F
- Fertilizer – A substance that is added to plants to promote their growth
- Filtration – The process of removing the fine particles in water by filters
- Fin – A limb and touch organ that fish use to move in the water
- Fish farm – The establishment where the fish are grown artificially
- Flat coast – A shallow coastal area where the land descends gradually into the sea
- Flippers – Broad, flattened limbs of mammals that are adapted for moving in the water
- Flow rate – The speed of the water movement in its riverbed
- Fluidity – The ability of a liquid to flow readily
- Fog – A layer of water droplets or ice crystals suspended in the air near the ground that reduces visibility
- Food chain – A sequence of organisms that feed off of each other
- Food web – A network of all the nutritional relationships in the community
- Freezing – The change of a liquid into a solid
- Frost – A thin layer of ice crystals formed on the ground
G
- Gas – A substance in a gaseous state
- Gills – Organs that allow organisms to obtain oxygen from water
- Glacier – A huge mass of ice that consists of compressed snow
- Gravity – The force a planet or other body uses to pull objects toward its centre
- Groundwater – The water that has accumulated underground in the cracks and spaces in soil and rocks
H
- High water – The water level rise in bodies of water, often accompanied with floods
- Humidity – The amount of water vapour in the air
K
- Karst spring – A spring that has formed by the dissolution of soluble rocks
- Karstification – The phenomenon where rainwater infiltrates the ground and dissolves the rocks there, leaving hollows and caves
L
- Lake – A water-filled depression with no direct connection to the sea
- Land breeze – Wind that blows from the land towards the sea during the night
- Liquid – A substance in a liquid state
M
- Mainstem – The river into which tributaries flow
- Mammal – A furry animal that feeds its offspring with milk
- Meander – A curve or a bend of a river
- Melting – The change of a solid into a liquid
- Melting point – The temperature at which the substance begins to melt
- Mineral water – Water that contains a lot of dissolved minerals or other solutes
- Mixture – A combination of 2 or more substances
- Molecule – A particle that is made of at least 2 atoms
- Moraine – The mixture of rocks and soil left behind by a moving glacier
- Mouth – The place where a river empties into the sea or a lake
N
- Natural resource – A part of the natural environment that is used and usable by humans
- Nitrogen – A gas that makes up most of the air
- Non-predatory fish – Fish that do not eat other fish
O
- Oligotrophic lake – A lake that lacks nutrients and vegetation
- Osmosis – A solution moving through a semipermeable coating, a.k.a. a membrane
- Oxbow lake – A u-shaped lake that is formed when a meander is cut off from a river
- Oxygen – A gas contained in the air which organisms need for respiration
- Ozone – A gas molecule composed of three oxygen atoms
- Ozone layer – The layer of ozone in the atmosphere that protects us from the harmful solar radiation
P
- Particle – A part of a substance that has the same properties as the substance
- Photosynthesis – The process by which plants produce nutrients from water and carbon dioxide using light energy; thereby releasing oxygen
- Polar regions – Areas surrounding the poles (the Arctic and the Antarctic)
- Pollen – The male sex cells of plants that are needed for the plant to produce seeds
- Pollination – The process of transferring pollen grains from the stamen part of a flower to the pistil part of a flower
- Precipitation – Any form of water that falls to Earth's surface due to condensation of water vapour
- Predatory fish – Fish that eat other fish
- Producer – An organism that produces the organic matter necessary for life from simple compounds
R
- Rapid – A fast-flowing part of the river in an uneven and rocky riverbed
- Reef – A rocky ridge underwater
- Reservoir – A body of water built on a river by constructing a dam
- Respiration – The process of breaking down nutrients using oxygen
- Rhizome – The underground stem of the plant
- Rime ice – The snow-like precipitation that can be seen as ice on a window or as sugar-like crumbs and crystals on cars, trees and plants
- River – A natural stream of flowing water
- River cliff – A vertical bank that forms on the outside of a meander where the water cuts into the floodplain
- River gradient – The slope of the river, measured by the elevation difference over a certain distance
- River system – The mainstem with its tributaries and distributaries
- Riverbed – The channel in which the river flows
S
- Salinity – A measure of the amount of dissolved salts in water
- Sand shoal – Shallow and flat, elongated sandy wall in a river or sea near the shore
- Sea breeze – Wind that blows from the sea towards land during the day
- Settling – The process by which solids settle to the bottom of the liquid
- Shoreline plants – A plant that grows on the border of water and land
- Skerry – A small island with only a few plants that is flooded at higher water levels
- Slip-off slope – The flat bank on the inside of the meander where sediments accumulate
- Solid – A substance in a solid state
- Solute – The substance that dissolves in a solvent
- Solution – A liquid consisting of a solvent and a solute
- Solvent – A liquid that dissolves a solute
- Source – The place at which a river begins
- Spring (the water source) – A place where groundwater emerges to the Earth's surface
- State of matter – The form of the substance, determined by the arrangement of the particles in the substance
- Steep coast – A coastal area where the land descends abruptly into the sea
- Straining – Pouring a liquid through a material or a device that separates out any solid matter
- Stratus clouds – Low, gray, dense clouds that form at altitudes of up to 2 km
- Submerged plant – A plant that grows fully in water
- Substance – A collection of identical molecules
- Supporting tissue – Tissue that allows organisms to stay upright
- Surface tension – A phenomenon in which the surface layer of a liquid acts as a film
T
- Thermal expansion – The tendency for substances to expand when heated
- Tributary – A river or stream flowing into a larger river
V
- Valley – A long depression in the ground
- Volatility – A measure of how easily a substance evaporates
W
- Wastewater – Water that has been used by humans and that is no longer clean
- Water cycle – The continuous circulation of water
- Water treatment plant – A place where wastewater is purified
- Waterfall – An area where water flows over a steep vertical drop
- Weather – The state of the atmosphere in a particular place at a particular time
- Wetting – Liquid molecules are attracted to solid surface molecules and the liquid spreads on the solid surface
- Wind – The horizontal movement of air above ground
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