Ordinary Thunderstorms

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If the updrafts reach the top of the troposphere, the cumulus cloud will begin to spread outward, creating a defined anvil. Such storms are rarely severe and are a result of local atmospheric instability; hence the term "air mass thunderstorm".

The NWS states that "a tornado is a violently rotating (usually counterclockwise in the northern hemisphere) column of air descending from a thunderstorm and in contact with the ground. To estimate how far you are from lightning, count the number of seconds between the flash of lightning and when you hear the thunder reach you, then divide by five. At the ground, the gust front moves out a long distance from the storm and cuts off the warm moist air that was feeding the thunderstorm. Now dry air is actually heavier than moist air, so when it infiltrates a storm system it can cause the mT air mass to rise much like a cold front without the cold. As the water vapor condenses into liquid, latent heat is released which warms the air, causing it to become less dense than the surrounding dry air.Supercells consist of a single powerful thunderstorm that can last several hours and grow to a height of 65,000 feet and last several hours in the mature stage with winds reaching over 100 mph and form the majority of all tornadoes. If this change in winds and instability is extreme in the lowest few thousand feet above the ground, as might occur near the warm front or low-pressure center in the map above, tornadoes – some strong – could develop within supercells.

On weather radar, storms are tracked by using a prominent feature and tracking it from scan to scan. Strong (up to more than 120 mph) straight-line winds associated with thunderstorms knock down trees, power lines and mobile homes. Ordinary Thunderstorms could have been a paint-by-numbers thriller, but Boyd quite deliberately plays with the form. Dissipating cells weaken on east or northeast edge (downwind) of cluster with the collective motion of the cluster also downwind. Ordinary Thunderstorms - combination fast-paced thriller and sprawling Charles Dickens-like London saga.As the air rises, it transfers heat from the surface of the earth to the upper levels of the atmosphere (the process of convection). A characteristic feature of the thunderstorm, viewed from a distance, is its cylindrical or slightly hourglass shape capped by an anvil-shaped top; the anvil is caused by air diverging from the upper portions of the storm’s updraft ( Figure T14). Any opinions, findings and conclusions or recommendations expressed in this material do not necessarily reflect the views of the National Science Foundation.