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Chapter 13
Vocabulary
| Term | Definition |
|---|---|
| Air mass thunderstorm | type of thunderstorm in which air rises because of unequal heating of Earth's surface within a single air mass and is most common during the afternoon and evening. |
| Mountain thunderstorm | occurs when an air mass rises from orographic lifting, which involves air moving up the side of a mountain. |
| Sea-breeze thunderstorm | local air-mass thunderstorm that commonly occurs along a coastal area because land and water store and release thermal energy differently. |
| Frontal thunderstorm | type of thunderstorm usually produced by an advancing cold front, which can result in a line of thunderstorms hundreds of kilometers long, or, more rarely, an advancing warm front, which can result in a relatively mild thunderstorm. |
| Stepped leader | the channel of partially charged air; the breakdown in charges in between positive and negative regions. |
| Return stroke | a branch channel of positively charged ions that rushes upward from the ground to meet the stepped leader. |
| Supercells | extremely powerful, self-sustaining thunderstorm characterized by intense,rotating updrafts. |
| Downburst | violent downdrafts that are concentrated in a local area. |
| Tornado | violent, whirling column of air in contact with the ground that forms when wind direction and speed suddenly change with height, is often associated with a supercell, and can be extremely damaging. |
| Fujita tornado intensity scale | classifies tornados according to their wind speed, duration, and path of destruction on a scale ranging from F0 to F5. |
| Tropical cyclone | large, low pressure, rotating tropical storm that gets its energy from the evaporation of warm ocean water and the release of heat. |
| Eye | calm center of a tropical cyclone that develops when the winds around its center reach at least 120 km/h. |
| Eyewall | band where the strongest winds in a hurricane are usually concentrated, surrounding the eye. |
| Saffir-Simpson hurricane scale | classifies hurricanes according to wind speed, potential for property damage, and potential for flooding in terms of the effect on the height of sea level on a scale ranging from Category 1 to Category 5. |
| storm surge | occurs when powerful, hurricane-force winds drive a mound of ocean water toward shore, where it washes over the land, often causing enormous damage. |
| Drought | extended period of well-below-average rainfall, usually caused by shifts in global wind patterns, allowing high pressure systems to remain for weeks or months over continental areas. |
| Heat wave | extended period of above average temperatures caused by large, high pressure systems that warm by compression and block cooler air mass. |
| Cold wave | extended period of below average temperatures caused by large, high pressure systems of continental polar or arctic origin. |
| Windchill index | measures the windchill factor, by estimating the heat loss from human skin caused by a combination of wind and cold air. |