Category Archives: Phenomena

A haboob is dust storm that can be several miles long, several thousand feet high, and can travel hundreds of miles. Haboobs are caused when an intense column of sinking air in a thunderstorm hits the ground and lofts soil particles into the air. These downdrafts, referred to as a microburst, can hit the ground at 50-80 mph and then spread in all directions. The resulting winds stir up dust and dirt from large arid areas which then get blown along in front of the approaching thunderstorm. The lofted particles can reach heights of 5000 ft and can extend up to 100 miles wide.

The name “haboob” is derived from the Arabian word ‘hab’, meaning ‘to blow,’ and was originally the name for a dust storm or sandstorm in the northern part of Sudan. Continue reading →

Lightning is a huge electrical discharge, or spark, that results from vigorous motions in thunderstorms.

Storms are composed of ice crystals and liquid water droplets. Winds inside the storm cause particles to rub against one another, causing electrons to be stripped off, making the particles either negatively or positively charged. The charges get grouped in the cloud, often negatively charged near the bottom of the cloud and positively charged up high. This is an electric field, and because air is a good insulator, the electric fields become incredibly strong. Eventually a lightning bolt happens, and the flow of electrons neutralizes the electric field. Continue reading →

“Heat dome” is a term used explain extreme heat conditions across large geographic regions.

The American Meteorological Society maintains a glossary of meteorological terms and defines a heat dome as, “An exceptionally warm air mass at middle latitudes during the warm season that that is associated with a synoptic-scale area of high pressure aloft. This area of high pressure aloft can have a doming effect on the warm air mass below by suppressing rising motion and the development of clouds and precipitation.” This is not the same as a heat wave, which is a spell of 3 or more abnormally hot days. Continue reading →

According to the American Meteorology Society’s glossary, a landspout is a colloquial name for a small tornado whose vorticity (a vector that measures local rotation in a fluid flow) originates in the boundary layer and has a parent cloud in its growth stage. Landspouts occur when colliding winds at the surface begin to make a vortex and then a developing thunderstorm passes overhead. The updrafts from that thunderstorm draw the rotating vortex upward and give it a tornado-like appearance. While relatively weak compared to traditional tornadoes, landspouts can be strong enough to cause damage and warrant caution.

The term “landspout” was coined by atmospheric scientists in the 1980s to describe a type of vortex associated with thunderstorms that do not possess a strong mid-level mesocyclone. A mesocyclone is a cyclonically rotating vortex, around 2–10 km in diameter, in a convective storm. Strong tornadoes form in mesocyclones.
Continue reading →