Earth Science Vocabulary 1. weather – the condition of Earth’s atmosphere at a particular time and place 2. atmosphere - the layer of gases surrounding the Earth 3. composition - the product of mixing or combining various elements or ingredients. The composition of our atmosphere is made up of nitrogen, oxygen and other gases. 4. water vapor – water in the form of a gas 5. mass – the amount of matter in an object 6. density- the mass of a substance contained in a unit of volume 7. volume – the amount of space an object takes up 8. pressure – the force exerted on a surface divided by the total area over which the force is exerted 9. air pressure – the pressure caused by the weight of a column of air pushing down on an area 10. barometer – an instrument used to measure changes in air pressure 11. altitude – elevation above sea level 12. troposphere – the lowest layer of Earth’s atmosphere where weather occurs 13. stratosphere – the second lowest layer of Earth’s atmosphere 14. mesosphere – the layer of Earth’s atmosphere immediately above the stratosphere; the layer in which most meteoroids burn up 15. thermosphere – the outermost layer of Earth’s atmosphere 16. ionosphere – the lower part of the thermosphere, where electrically charged particles called ions are found 17. exosphere – the outer layer of the thermosphere, extending outward into space 18. pollution – the contamination of Earth’s land, water or air 19. pollutants – harmful substances in the air, water or soil 20. particle pollution – tiny particles of dust, dirt, smoke and liquid droplets in the air 21. ozone layer- the layer of the atmosphere that contains a higher concentration of ozone that the rest of the atmosphere. Ozone in the form of smog in the troposphere is a pollutant (bad!) Ozone in the stratosphere protects us from ultra violet radiation (good!) 22. photochemical smog – a brownish haze that is a mixture of ozone and other chemicals, formed when pollutants react with each other in the presence of sunlight 23. acid rain – rain that contains more acid than normal 24. electromagnetic waves – waves that can transfer electric and magnetic energy through the vacuum of space 25. temperature – a measure of how hot or cold an object is compared to a reference point 26. thermal energy – the total energy of motion in the particles of a substance 27. thermometer – an instrument used to measure temperature, consisting of a thin glass tube with a bulb on one end that contains a liquid (usually mercury or alcohol) 28. heat – the transfer of thermal energy from one object to another because of a difference in temperature 29. conduction – the direct transfer of thermal energy from one substance to another substance that it is touching 30. convection – the transfer of thermal energy by the movement of a fluid 31. convection currents – the circulation of a fluid as it alternately heats up and cools down; in weather, upward movement of warm air and the downward movement of cool air. 32. radiation – the direct transfer of energy by electromagnetic waves. 33. wind – the horizontal movement of air from an area of high pressure to an area of low pressure 34. anemometer – an instrument used to measure wind speed 35. wind vane – an instrument used to measure wind direction 36. wind-chill factor – a measure of cooling combining temperature and wind speed 37. local winds – winds that blow over a short distance 38. sea breeze – the flow of cooler air from over an ocean or lake toward land 39. land breeze – the flow of air from land to a body of water 40. global winds – winds that blow steadily from specific directions over long distances 41. Coriolis effect – the change that Earth’s rotation causes in the motion of objects and that explains how winds curve 42. latitude – the distance in degrees north or south of the equator 43. jet streams- bands of high-speed winds about 10 km above Earth’s surface 44. water cycle – the continual movement of water among Earth’s atmosphere, oceans and land surface through evaporation, condensation and precipitation. 45. evaporation – the process by which water molecules in liquid water escape into the air as water vapor. 46. condensation – the process by which molecules of water vapor in the air become liquid water 47. precipitation – any form of water that falls from clouds and reaches Earth’s surface 48. transpiration – the process by which water is lost through a plant’s leaves 49. humidity – the amount of water vapor in a given volume of air 50. relative humidity – the percentage of water vapor in the air compared to the maximum amount of water vapor that air can contain at a particular temperature 51. psychrometer – an instrument used to measure relative humidity, consisting of a wet-bulb thermometer and a dry-bulb thermometer. 52. cirrus clouds – wispy, feathery clouds made mostly of ice crystals that form at high altitudes. 53. cumulus clouds – fluffy, white clouds, usually with flat bottoms, that look like rounded piles of cotton. 54. stratus clouds – clouds that form in flat layers and often cover much of the sky. “strato” means “spread out” 55. nimbus – this suffix means “rain” A cumulonimbus cloud is a towering cloud with a flat top that produces thunderstorms 56. rain gauge – an instrument used to measure precipitation 57. air mass – a huge body of air that has similar temperature, humidity and air pressure throughout 58. front – the boundary where unlike air masses meet 59. occluded – cut off, as in a front where a warm air mass is caught between two cooler air masses 60. cyclone – a swirling center of low air pressure 61. anticyclone – a high-pressure center of dry air 62. meteorologist – scientist who studies the causes of weather and try to predict it 63. weather balloon – carry instruments high into the troposphere and lower stratosphere to measure temperature, air pressure and humidity 64. weather satellite – orbit in the exosphere where cameras make images of Earth’s surface, clouds, storms and snow cover 65. automated weather stations – surface locations gather data on temperature, air pressure, relative humidity, rainfall and wind speed and direction. 66. weather map – a “snapshot” of conditions at a particular time over a large area 67. Doppler radar – tracks intensities, speed and direction of precipitation via radio waves .