• mist
    Different temperatures cause water vapor to condense and form mist over a lake.

    Gorillas in the Mist
    Zoologist Dian Fossey studied mountain gorillas and their behavior over 18 years in the African country of Rwanda. Her famous book about the experience is called Gorillas in the Mist.

    Mist is tiny droplets of water hanging in the air. These droplets form when warmer water in the air is rapidly cooled, causing it to change from invisible gas to tiny visible water droplets.

    Mist often forms when warmer air over water suddenly encounters the cooler surface of land. However, mist can also form when warm air from land suddenly encounters cooler air over the ocean. This is the cause of the summer fog in San Francisco, California. You can even create mist yourself, as you probably know, when you exhale the warm air from your body into the cold air.

    Mist is a lot like its cousin, fog. The difference between the two depends on how well you can see. Mist is less dense than fog. If you can't see beyond one kilometer (two-thirds of a mile) in front of you, it's fog that's clouding your vision. If you can see more than that, it's just mist.

    Mist caused by volcanic activity is simply hot water vapor expelled along with gases and, sometimes, lava, by a volcano. Volcanic mists are emitted by steam vents, or cracks in the Earth's surface around volcanoes and geysers. Sometimes, volcanic mists are watery clouds you can walk through. Steam vents are popular tourist attractions at Volcanoes National Park in the U.S. state of Hawaii, for example.

    Sometimes, however, these volcanic mists have other chemicals in them, often causing distinct odors. Volcanologists study the chemical properties of these mists to see what rocks and gases are under the volcano. They also measure the temperature. The hotter the steam, the more likely the volcano is to erupt. A difference of only a few degrees can mean the difference between a nice mist and a steam explosion.

    You'll find mist all over the world. Some of the world's most famous foggy spots, such as Scotland, in the United Kingdom, are also home to mist. Scotch mist, in fact, is a very light, steady drizzle of rain.

  • Term Part of Speech Definition Encyclopedic Entry
    behavior Noun

    anything an organism does involving action or response to stimulation.

    chemical Noun

    molecular properties of a substance.

    chemical property Noun

    unique identity of a substance expressed by its type and arrangement of molecules.

    Dian Fossey Noun

    (1932-1985) American zoologist.

    distinct Adjective

    unique or identifiable.

    drizzle Noun

    very light rain.

    erupt Verb

    to explode or suddenly eject material.

    exhale Verb

    to breathe out.

    expel Verb

    to eject or force out.

    fog Noun

    clouds at ground level.

    Encyclopedic Entry: fog
    gas Noun

    state of matter with no fixed shape that will fill any container uniformly. Gas molecules are in constant, random motion.

    geyser Noun

    natural hot spring that sometimes erupts with water or steam.

    Encyclopedic Entry: geyser
    lava Noun

    molten rock, or magma, that erupts from volcanoes or fissures in the Earth's surface.

    mist Noun

    clouds at ground-level, but with greater visibility than fog.

    Encyclopedic Entry: mist
    mountain Noun

    landmass that forms as tectonic plates interact with each other.

    mountain gorilla Noun

    mammal (primate) native to Africa.

    odor Noun


    rapidly Adverb


    rock Noun

    natural substance composed of solid mineral matter.

    sauna Noun

    room in which steam causes visitors to sweat.

    scotch mist Noun

    fog and drizzle.

    steam explosion Noun

    violent expansion of liquid water into vapor. Also called a littoral explosion.

    steam room Noun

    chamber filled with water vapor, used in spas or parts of saunas.

    steam vent Noun

    cracks in the Earth near volcanoes or geysers where water is heated by volcanic activity.

    temperature Noun

    degree of hotness or coldness measured by a thermometer with a numerical scale.

    Encyclopedic Entry: temperature
    tiny Adjective

    very small.

    vapor Noun

    visible liquid suspended in the air, such as fog.

    volcanic Adjective

    having to do with volcanoes.

    volcanologist Noun

    scientist who studies volcanoes.

    weather Noun

    state of the atmosphere, including temperature, atmospheric pressure, wind, humidity, precipitation, and cloudiness.

    Encyclopedic Entry: weather
    zoologist Noun

    person who studies animals.

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