The site editor may also be contacted with questions or comments about this Open Educational Resource. In severe thunderstorms, this cycle is extended because of differences in the inflow of warm, moist air into the thunderstorm. As long as the updraft can keep feeding the thunderstorm warm, humid air, it will continue to grow and intensify. We'll explore further beginning in the next section. The bottom line here is that the mature stage of a single-cell thunderstorm is exactly what its name suggests--a period when the storm is the most vigorous. When the moisture condenses, it releases energy known as latent heatof condensation, which allows the rising packet of air to cool less than the cooler surrounding air contin… When you're finished with this section, you should be able to describe the life cycle of a single-cell thunderstorm (including characteristics of the cumulus, mature, and dissipating stages). As you can imagine, the wind behind the gust front can be very strong, sometimes even reaching severe levels. However, most storms cool things off a more modest 10-15 degrees because of evaporative cooling. You can think of a downdraft as a blob of cool air in the cloud that is heading toward the earth’s surface (opposite of an updraft). Meteorologists refer to the gathering "puddle" of rain-cooled air spreading out along the ground as a "cold pool," which in general tends to be about one to two kilometers deep. In the towering cumulus stage, the rising updraft will suspend growing raindrops until the point where the weight of the water is greater than what can be supported. Warm air has a lower density than cool air, so warmer air rises upwards and cooler air will settle at the bottom (this effect can be seen with a hot air balloon). Cut off from a supply of buoyant, maritime-Tropical air, the single cell's updraft weakens. Once downdrafts become dominant and a storm "rains itself out" as the cold pool grows larger and cuts off the storm from warm, moist air for its updraft, the storm dies. Let's explore the process, as we investigate the first stage in a single-cell thunderstorm's life cycle -- the cumulus stage. A basic thunderstorm (single cell) goes through three phases during its lifetime: cumulus, mature, and dissipating. If the updraft is slanted, then the rain that falls out of the cloud will not cut off the inflow of the moist air that is the thunderstorm's fuel, allowing it to continue for a much longer time period. They are typically driven by heating on a summer afternoon. Course Author: Steven Seman (Assistant Teaching Professor, Department of Meteorology and Atmospheric Science, College of Earth and Mineral Sciences, Multicell Cluster Storms A group of cells moving as a single unit, with each cell in a different stage of the thunderstorm life cycle. The photograph of multicell thunderstorms below, taken on June 12, 2016 in Duck, North Carolina, shows a cluster of cumulus clouds in various stages of development. Gust fronts associated with single-cell thunderstorms can spark other thunderstorms (warm, moist air converging at the gust front is forced to rise), but, most times they don't. Think about it: "Random" thunderstorm development would mean that they develop on a whim, for no reason at all. When air parcels rise to the top of the troposphere, they quickly become cooler than their surroundings above the tropopause (the stratosphere is stable), which means they become negatively buoyant and slow to a halt. The unstable air should be somewhat warm and able to rise rapidly. An air-mass thunderstorm, also called an "ordinary", "single cell", or "garden variety" thunderstorm, is a thunderstorm that is generally weak and usually not severe. Figure C. A Gust Front located ahead of an approaching thunderstorm. Note the simultaneous presence of an updraft and a downdraft. The presence of towering cumulus indicates a dramatic change in the tenor of the convection. Cooling associated with evaporating cloud drops increases the density and reduces the buoyancy of the air parcels, and by the time the cumulus builds to a depth of about one and a half times its diameter at the lifting condensation level, the air loses its buoyancy. Looking for a snack to hold you over until Thanksgiving? Depending on thunderstorm type, a storm may go through it only once (single cell), or multiple times (multi-cell). The Pennsylvania State University). Single cell thunderstormSingle cell thunderstorm stagesstages The meteorologically-assignedcloud type associated with the thunderstorm is cumulonimbus Most common; last for less than an hour; built-in self-destruct mechanism; occur all year long, but mostly in summer; can produce strong winds, lightning, hail, and microbursts; three stages of growth Single-Cell Thunderstorms: A textbook, run of the mill single storm that develops, grows, and dies like described above would be classified as a single-cell thunderstorm. Sinking air in the downdraft causes small cloud droplets to evaporate, and once the updraft fades, residual raindrops can "scavenge" cloud droplets as they fall, further eating away at the cumulonimbus cloud. At that level the raindrops collide and join into larger droplets due to the churning turbulence in the cloud. However, after a thunderstorm passed through the area, the downdraft dropped the temperature to a cool 57 degrees by 5:00 P.M., a 40 degree temperature swing in one hour! Figure A. It did not produce any severe weather. When downdrafts "splashdown" at the ground and spread out, they can produce gusty winds. A multi-cell storm is a common, garden-variety thunderstorm in which new updrafts form along the leading edge of rain-cooled air (the gust front). New cumulus clouds often develop in the same column as the original cumulus, and they benefit from the water vapor from cloud droplets that evaporated earlier. For example, during a hot, summer afternoon in Sattley, California, the temperature was a blazing 97 degrees at 4:00 P.M. In the dissippating stage of a single-cell thunderstorm, the cloud is dominated by downdrafts, and a large area of precipitation and cold outflow are present. Most thunderstorms undergo three phases in their formation, namely: 1. After splashdown, the leading edge of this horizontally spreading rain-cooled air is called a gust front or, more formally, an outflow boundary (because it is a boundary between rain-cooled air and the unmodified air mass). In reality, positively buoyant air parcels that comprise the updraft of a growing cumulus cloud actually do mix with surrounding cooler, drier air in a process called entrainment, which is bad news for aspiring cumulus clouds. Downdrafts develop for essentially two reasons: the drag exerted by falling raindrops, and cooling associated with the evaporation of small raindrops (via entrainment). If there's a sufficient supply of low-level moisture and persistent positively buoyant parcels over time, a succession of cumulus clouds can now grow and ebb in a single column of air. You may think of a gust front as a miniature cold front. A schematic of the mature stage of a single-cell thunderstorm. Why do I care? Still, sometimes thunderstorms seem awfully disorganized. Figure B. Indeed, the rain-induced downdraft that splashes down and spreads out laterally inevitably cuts off the inflow of warm, humid air into the storm's updraft.