**ash**: (in geology) Small, lightweight fragments of rock and glass spewed by volcanic eruptions.
**atom**: The basic unit of a chemical element. Atoms are made up of a dense nucleus that contains positively charged protons and uncharged neutrons. The nucleus is orbited by a cloud of negatively charged electrons.
**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.
**current**: A fluid — such as of water or air — that moves in a recognizable direction. (in electricity) The flow of electricity or the amount of charge moving through some material over a particular period of time.
**electric charge**: The physical property responsible for electric force; it can be negative or positive.
**electric current**: A flow of electric charge — electricity — usually from the movement of negatively charged particles, called electrons.
**electricity**: A flow of charge, usually from the movement of negatively charged particles, called electrons.
**electron**: A negatively charged particle, usually found orbiting the outer regions of an atom; also, the carrier of electricity within solids.
**environment**: The sum of all of the things that exist around some organism or the process and the condition those things create. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature and humidity (or even the placement of things in the vicinity of an item of interest).
**eruption**: (in geoscience) The sudden bursting or spraying of hot material from deep inside a planet or moon and out through its surface. Volcanic eruptions on Earth usually send hot lava, hot gases or ash into the air and across surrounding land. In colder parts of the solar system, eruptions often involve liquid water spraying out through cracks in an icy crust. This happens on Enceladus, a moon of Saturn that is covered in ice.
**generator**: A device used to convert mechanical energy into electrical energy.
**insect**: A type of arthropod that as an adult will have six segmented legs and three body parts: a head, thorax and abdomen. There are hundreds of thousands of insects, which include bees, beetles, flies and moths.
**ion**: (adj. ionized) An atom or molecule with an electric charge due to the loss or gain of one or more electrons. An ionized gas, or plasma, is where all of the electrons have been separated from their parent atoms.
**lightning**: A flash of light triggered by the discharge of electricity that occurs between clouds or between a cloud and something on Earth’s surface. The electrical current can cause a flash heating of the air, which can create a sharp crack of thunder.
**metal**: Something that conducts electricity well, tends to be shiny (reflective) and is malleable (meaning it can be reshaped with heat and not too much force or pressure).
**physics**: The scientific study of the nature and properties of matter and energy. Classical physics is an explanation of the nature and properties of matter and energy that relies on descriptions such as Newton’s laws of motion. Quantum physics, a field of study that emerged later, is a more accurate way of explaining the motions and behavior of matter. A scientist who works in such areas is known as a physicist.
**plume**: (in geology) Fluids (air, water or magma typically) that move, largely intact, in a feather-like shape over long distances.
**pollen**: Powdery grains released by the male parts of flowers that can fertilize the female tissue to make a seed. Pollinating insects, such as bees, often pick up pollen that will later be eaten.
**sensor**: A device that picks up information on physical or chemical conditions — such as temperature, barometric pressure, salinity, humidity, pH, light intensity or radiation — and stores or broadcasts that information. Scientists and engineers often rely on sensors to inform them of conditions that may change over time or that exist far from where a researcher can measure them directly.
**static electricity**: The buildup of excess electric charge on some surface instead of flowing through a material. This charge buildup tends to develop when two things that are not good conductors of electricity rub together. This allows electrons from one of the objects to be picked up and collected by the other.
**swarm**: A large number of animals that have amassed and now move together. People sometimes use the term to refer to huge numbers of honeybees leaving a hive.
**trade**: The buying, selling or swapping of goods or services — indeed, of anything that has value.
**triboelectric**: An adjective to describe an electric charge that develops when two things rub against each other, causing friction.