Air Masses are large bodies of air that have fairly uniform physical properties, such as the temperature and moisture content, at any given altitude. An air mass forms when a large body of air stays stationary over a region of Earth's surface, or if a large air mass moves over a uniform region, such as the ocean. They are classified according to the location they form on, such as water or land, and the latitude. There are four types of air masses, continental tropical, continental polar, maritime tropical, and maritime polar. When two unlike air masses meet, a sharply defined boundary called a front emerges. A cold front occurs when a cold air mass overtakes a warm air mass. Similarly, a warm front occurs when a warm air mass overtakes a cold air mass. Since cold air more dense than warm air, it remains close to the ground, while the moist, warm air condenses and rises. Additionally, there are two fronts called the stationary front, and the occluded front. A stationary front occurs when two unlike air masses form a boundary, but neither is moving. An occluded front occurs when when a warm air mass in trapped between two cold air masses.
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ThunderstormsThunderstorms are small weather systems that include thunder and lightning. They occur when columns of air rise within a cumulonimbus cloud.
Lightning is a sudden electrical discharge in the atmosphere during a thunderstorm. Thunder is the sound produced by rapidly expanding air along the path of a lightning discharge. |
HurricanesHurricanes are large, swirly storms. Hurricanes classify as tropical cyclones. It is a low pressure system formed in the tropics.
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TornadoesTornadoes appears as a twisting funnel cloud descending from the bottom of a cumulonimbus cloud. For tornadoes to form, there must be a large difference in the two air masses colliding with each other.
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