Tag Archives: Phenomena
Lightning is a huge electrical discharge that results from the rising and sinking air motions that occur in thunderstorms. Lightning can be either cloud-to-cloud or cloud-to-ground and is accompanied by thunder. Lighting also has different appearances. Continue reading
A derecho (pronounced deh-RAY-cho, a Spanish word meaning “straight ahead”) is an hours-long windstorm associated with a line of severe thunderstorms. It is a result of straight-line winds, not the rotary winds of a tornado — hence its name. Derechos in the United States are most common in the late spring and summer (May through August). Continue reading
Recently, the Duluth-Superior metro area had devastating flooding a result of rainfall totals of 10 inches or more in some locations. You may have seen photographs of the damage wrought by the flood waters — washed-out roads, flooded homes, ruined crops, etc.
Even in the face of such dramatic damage it is easy to overlook the enormous amount of energy that is involved in simply processing the water involved in such enormous amounts of precipitation. Continue reading
A flood occurs when water flows into a region faster than it can be absorbed into the soil, stored in a lake or reservoir or removed in runoff or a waterway into a drainage basin.
A flash flood is a sudden local flood characterized by a great volume of water and a short duration. It occurs within minutes or hours of heavy rainfall or because of a sudden release of water from the breakup of an ice dam or constructed dam. Continue reading
A pyrocumulus cloud forms from rising air that results from intense heating of the surface by phenomena such as wildfires or volcanic eruptions. The fires that generate these clouds can be man-made or natural. A big fire produces strong upward moving air currents that carry water vapor and ash upward. The water vapor can condense on the ash forming cloud drops. The vigorous upward motions produce these pyrocumulus clouds that look similar to thunderstorm clouds, which also form due to strong upward moving air. Continue reading