Global and Local Winds in Zimbabwe

Zimbabwe is a African country at coordinates 19.0167 degrees south latitude, 30.0167 degrees east longitude. This puts Zimbabwe in the Southern Hemisphere, well within the tropics (from 23.5 degrees south to 23.5 degrees north latitude). According to the three cell model of global circulation discussed in lecture, Zimbabwe lies within the Hadley cell of atmospheric circulation (from 0-30 degrees north or south latitude). The Hadley cell consists of rising warm air at the equator cooling and moving towards 30 degrees N or S latitude where the air sinks and moves back towards the equator. The pressure gradient force is towards the equator from the location of the sinking air at 30 degrees S. In the southern hemisphere, the Coriolis Effect curves wind to the left, and friction in the opposite direction of the PGR curves the wind back towards the PGF. This explains the direction of the trade winds, which is the wind belt that Zimbabwe resides in. Though the trades blow east to west, the prevailing wind direction in Zimbabwe is hardly defined due to the location of Madagascar off the coast of Eastern Africa and how drastically it influences wind direction. Zimbabwe is located in the ITCZ, or Intertropical Convergence Zone, which is a main low pressure system that varies in latitude depending on the time of year. January is when Zimbabwe lies within the ITCZ, and is subsequently right in the middle of Zimbabwe's rainy season. Because Zimbabwe is within the ITCZ in January, it is also within the doldrums during this time. Doldrums are where the northern and southern trade winds meet at the equator  and creates an area of highly variable weather.

image from http://www.weatherwizkids.com/globalcirculation.gif

Zimbabwe's climate is directly affected by global wind patterns and pressure systems relevant to it's location. Zimbabwe's location at 19 degrees S puts it in the Hadley cell, which means wind is generally moving from east to west. This means that future weather can be predicted by looking at what type of pressure systems are developing over the Indian Ocean being that the wind is most likely going to blow this weather westward. Also Zimbabwe is very characteristic of tropical countries in that it has a distinct wet and dry seasons. This is due to the ITCZ shifting throughout the year and in January is when Zimbabwe lies within the ITCZ. In past years when the ITCZ wasn't very well defined, Zimbabwe experienced drought-like climate, and in past years when the ITCZ was very well defined, Zimbabwe receives average to higher than average rainfall. The rainy season occurs when the ITCZ approaches and reaches Zimbabwe, and the rest of the year receives essentially zero rainfall. This makes it easy to predict the weather of Zimbabwe during any time of the year.

Zimbabwe has many mountains, from the Bvumba Mountains to the Eastern Highlands. The 5 types of breezes associated with mountains is the Chinook Winds, Santa Ana Winds, Katabatic Winds, Valley breezes and mountain breezes. Most of Zimbabwe's higher-elevation terrain is located on the eastern side of the country, though it has a minor effect of the wind direction because of the location of Madagascar, and how Madagascar actually is the main contributor to the unique winds in Zimbabwe. Because the trade winds blow from east to west and Madagascar lies east of Zimbabwe, the trade winds' path is blocked and deviated around the island, resulting in a northwestern prevailing wind direction. Madagascar also acts as a barrier to severe weather systems heading directly towards Mainland Africa, weakening and deviating it's path which lowers the instances of weather related disasters.

image from http://www.windfinder.com/weather-maps/forecast/zimbabwe#4/-12.38/41.31

Because Zimbabwe is landlocked, it is not directly affected by coastline breezes, such as land and sea breezes. The closest body of water is the Mozambique Channel, almost 500 miles away.