Arctic: A region that falls within the Arctic Circle. The edge of that circle is defined as the northernmost point at which the sun is visible on the northern winter solstice and the southernmost point at which the midnight sun can be seen on the northern summer solstice. The high Arctic is that most northerly third of this region. It’s a region dominated by snow cover much of the year.
atmosphere: The envelope of gases surrounding Earth, another planet or a moon.
average: (in science) A term for the arithmetic mean, which is the sum of a group of numbers that is then divided by the size of the group.
blackout: (in energy) The loss of electric power to a broad area, and so named because all of the electric lights in the affected area will blink off when this occurs (unless they have a backup electric generator).
blow: (noun) A term for the materials exhaled by whales through their blowholes. This can include air, mucus, germs and sometimes even seawater.
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.
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.
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.
drought: An extended period of abnormally low rainfall; a shortage of water resulting from this.
global warming: The gradual increase in the overall temperature of Earth’s atmosphere due to the greenhouse effect. This effect is caused by increased levels of carbon dioxide, chlorofluorocarbons and other gases in the air, many of them released by human activity.
heat exhaustion: An illness that can result from prolonged heat exposure. Symptoms include extreme sweating, fast breathing and a weak pulse. Without treatment, heat exhaustion can turn into heat stroke.
heat stroke: A dangerous illness that can result from prolonged heat exposure. Symptoms tend to include dry skin and a fast heartbeat. Sufferers also may feel dizzy, nauseated and confused. Heat stroke can be fatal.
jet stream: A fast-flowing, high-altitude air current. On Earth, the major jet streams flow from west to east in the mid-latitude regions of the Northern and Southern Hemispheres.
link: A connection between two people or things.
livestock: Animals raised for meat or dairy products, including cattle, sheep, goats, pigs, chickens and geese.
meteorology: (adj. meteorological) The study of weather as it pertains to future projects or an understanding of long-term trends (climate). People who work in this field are called meteorologists.
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.
organ: (in biology) Various parts of an organism that perform one or more particular functions. For instance, an ovary is an organ that makes eggs, the brain is an organ that makes sense of nerve signals and a plant’s roots are organs that take in nutrients and moisture.
poles: (in Earth science and astronomy) The cold regions of the planet that exist farthest from the equator; the upper and lower ends of the virtual axis around which a celestial object rotates. (in physics and electrical engineering) The ends of a magnet. (in chemistry) two areas of opposite electrical charge, one positive and one negative.
pressure: Force applied uniformly over a surface, measured as force per unit of area.
risk: The chance or mathematical likelihood that some bad thing might happen. For instance, exposure to radiation poses a risk of cancer. Or the hazard — or peril — itself. (For instance: Among cancer risks that the people faced were radiation and drinking water tainted with arsenic.)
system: A network of parts that together work to achieve some function. For instance, the blood, vessels and heart are primary components of the human body’s circulatory system. Similarly, trains, platforms, tracks, roadway signals and overpasses are among the potential components of a nation’s railway system. System can even be applied to the processes or ideas that are part of some method or ordered set of procedures for getting a task done.
tropics: The region near Earth’s equator. Temperatures here are generally warm to hot, year-round.
urban: Of or related to cities, especially densely populated ones or regions where lots of traffic and industrial activity occurs. The development or buildup of urban areas is a phenomenon known as urbanization.
urban heat island: A city or metropolitan area that’s much warmer than surrounding rural areas. The increased temperature results from several phenomena. Many hard surfaces, such as buildings and pavements, absorb sunlight and then release that energy — as heat — into the air. Also, human activities such as running air conditioners and driving cars will release large amounts of heat directly into the environment.
weather: Conditions in the atmosphere at a localized place and a particular time. It is usually described in terms of particular features, such as air pressure, humidity, moisture, any precipitation (rain, snow or ice), temperature and wind speed. Weather constitutes the actual conditions that occur at any time and place. It’s different from climate, which is a description of the conditions that tend to occur in some general region during a particular month or season.
