Severe Weather in Zimbabwe

Tornadoes:    

The obvious description of a tornado is a massive rotating column of air. How in fact though does this cyclone begin to form? The answer to this is simply wind shear, which is when winds at two different altitudes blow at different speeds creating wind shear. This causes a horizontal rotating column of air, which is called the mesocyclone. If this column of air meets with a supercell updraft, the spin tightens, and goes from horizontal to vertical. The rain and hail in the thunderstorm then causes the funnel to touch down to the ground, creating a tornado.

      In the U.S. most tornados move from Southwest to Northeast or West to East. This is because the tornado themselves move with the thunderstorm that they are associated with, and they move in such a way due to the warm high pressure gulf air meeting the cold air from the North creating an upper level jet stream through the country, which moves from West to East with a wave like pattern.

     Fortunately, Zimbabwe rarely experiences tornados if they ever do. I could not come up with an accurate number of tornadoes each year, but from reading some articles from national geographic, it seems that it is rare to even see one every few years, with most of the sightings being actually just waterspouts. The reason it is uncommon is because of Zimbabwe’s unique geographic location. It is protected from the NE trades and even though it is located relatively close to a very active spot in South Africa, the island of Madagascar actually protects Zimbabwe from the prevailing winds and diverts the air down south where tornados occur much more frequently. Each year, the U.S. experiences 1253 tornadoes on average.

http://www.spc.noaa.gov/faq/tornado/

    I personally think that tornados have increased over time due to global warming. This is because tornadoes are associated with warm, and moist air because that is what is necessary for formation of the thunderstorms that these tornados are attached to. So with the increase in global temperature due to our release of greenhouse gasses, we are directly increasing that amount of warm and moist air, which in turn increases storm production and the tornadoes that come with that.

Hurricanes:

    The three big requirements for a hurricane are Warm ocean temperatures of at least 80 degrees F or higher, a deep and warm ocean layer that reaches down to at least 200m, and the coriolis effect that is needed to start the rotation for a hurricane and this occurs between > 5 Degrees N, S.

    The three main regions where hurricanes occur are the Atlantic and the East Pacific (Hurricanes), in the Indian Ocean near Australia (Cyclones), and off the coast of China and Indonesia (Typhoons).

     The general path of Hurricanes in the US start from the Atlantic, then move West where they come closer to our coasts where they then begin to move in a Northeastern fashion. The reason they move in this fashion is because at the origin, the trade winds move it up and to the west. When it comes closer to the U.S. however, the hurricanes meet our prevailing Westerlies, which change its direction to Southwest to Northeast relatively to our country. Hurricanes are actually very uncommon in Zimbabwe as well. This again is because of the unique geographical location of Zimbabwe and how Madagascar protects it from the prevailing winds as well as diverts the moving air to lower latitudes. This basically spares Zimbabwe altogether from the destruction of Hurricanes so that makes the average number 0 hurricanes a year. The average number of hurricanes in the U.S. stands to be a little higher with an impressive range of anywhere between 2 – 12 a year in the Atlantic Basin.

http://scienceline.ucsb.edu/getkey.php?key=1086