4th Science Unit D Review Atmosphere- Air that surrounds our planet. Air pressure- Air particles pressing down on a surface. TroposphereLayer of the atmosphere that is closest to the earth’s surface. Greenhouse EffectHeat from the sun is trapped in the atmosphere to warm earth. FrontBorder formed where a cold air mass and a warm air mass meet. Barometerpressure. Anemometerspeed. Humidityair. An instrument that measures air An instrument that measures wind The amount of water vapor in the Troposphere- Where most weather occurs. Warm Air- Low pressure, Less dense. Cold Air- High pressure, more dense. Wind Speed- Measured in km/hr. (kilometers/hour) Temperature- Precipitation- Measured in degrees. Measured in centimeters. ErosionMakes a beach smaller because it carries sand and sediment away from the shore. Gravitational force of the Moon on Earth’s oceans is stronger than the gravitational force of the sun because the moon is closer. Deep Ocean Currentbeneath less dense water. Inner Planetsbelt and the sun. Dense water flows Planets between the asteroid Gas Giantsmade mostly of gases. The 4 outer planets. Large spheres OrbitThe path an object takes when revolving around another object. Outer Planets- Cometsun. Jupiter, Saturn, Uranus, Neptune. Small mass of ice and dust that orbits the Solar Systemmove around it. A central star and objects that AsteroidsSmall rocky objects that move between the orbits of Mars and Jupiter. Telescopedistant object. Constellation- An instrument used to observe a A group of stars that forms a pattern. Star- A burning sphere of gases. Planet- A large object that moves around a star. Earth has liquid water. Axis- An imaginary line that earth rotates around. Sunin our solar system. The source of almost all the energy