the Dust Bowl

<< < (2/21) > >>

Mishe Vanatta:
Physical and environmental impacts

A sandstorm can move whole sand dunes. Dust storms can carry large amounts of dust, so much so that the leading edge of one can appear as a solid wall of dust as much as 1.6 km (1 mile) high. Dust and sand storms which come off the Sahara Desert are locally known as a simoom or simoon (smūm, smūn). The haboob (həbūb) is a sandstorm prevalent in the region of Sudan around Khartoum.

The Sahara desert is a key source of dust storms, particularly the Bodl Depression and an area covering the confluence of Mauritania, Mali, and Algeria.

Saharan dust storms have increased approximately 10-fold during the half-century since the 1950s, causing topsoil loss in Niger, Chad, northern Nigeria, and Burkino Faso. In Mauritania there were just two dust storms a year in the early 1960s, but there are about 80 a year today, according to Andrew Goudie, a professor of geography at Oxford University. Levels of Saharan dust coming off the east coast of Africa in June (2007) were five times those observed in June 2006, and were the highest observed since at least 1999, which may cool Atlantic waters enough to slightly reduce hurricane activity in late 2007.

Mishe Vanatta:
Economic impact

Dust storms cause soil loss from the dry lands, and worse, they preferentially remove organic matter and the nutrient-rich lightest particles, thereby reducing agricultural productivity. Also the abrasive effect of the storm damages young crop plants. Other effects that may impact the economy are: reduced visibility affecting aircraft and road transportation; reduced sunlight reaching the surface; increased cloud formation increasing the heat blanket effect; high level dust sometimes obscures the sun over Florida; effects on human health of breathing dust.

Dust can also have beneficial effects where it deposits: Central and South American rain forests get most of their mineral nutrients from the Sahara; iron-poor ocean regions get iron; and dust in Hawaii increases plantain growth. In northern China as well as the mid-western U.S., ancient dust storm deposits known as loess are highly fertile soils, but they are also a significant source of contemporary dust storms when soil-securing vegetation is disturbed.

Mishe Vanatta:
Notable dust storms

A series of dust storms displaced hundreds of thousands of agricultural workers in the central United States and Canada during the Dust Bowl.
A dust storm that occurred near Tucson, Arizona, USA on July 16, 1971 was extensively documented by meteorologists.
On the afternoon of February 8, 1983, a huge dust storm originating in the Mallee region of Victoria, Australia covered the city of Melbourne.
On Saturday afternoon of February 24, 2007, a large dust storm originating in the West Texas area of Amarillo covered much of the North Texas area. Strong winds caused extensive property damage to fences, roof shingles, and some buildings. The DFW Airport was severely affected, causing extensive flight delays into and out of the DFW area. Area residents suffered respiratory problems and allergic reactions, causing many people to visit hospitals. This event was also marked by relative humidities down to 1 per cent, in one case the juxtaposition of a c. 70°F air temp and dew point of -20°F, in and around of the area affected.
The multi-year droughts in portions of North America of 1954-56, 1976-78, and 1987-91 were noted for dust storms of the intensity seen in the middle 1930s over some fraction of their coverage and timespan, and more sporadically during the times between. The three multi-year droughts were similar to the 1930s in storms being raised by synoptic scale weather events such as cyclones and cold fronts; otherwise the most common trigger is the outflow from convective activity, known as a haboob. Significant events of the latter variety occurred in Colorado and Kansas in May 2004 with winds to 100 mph, Minnesota and Wisconsin in June 2004 causing significant damage, and the upper Middle West in May 1988, notable for strong electrification and lightning activity and by one estimate reaching 30 000 ft or more. The first and third of this list reached black blizzard intensity, causing total blackout for some period ranging from 90 sec to 10 or more minutes, over some fraction of the ground covered. The 1987-91 drought was especially notable as in the 1930s for the large number of rain of mud events, often generated by dust in suspension and/or carried on upper-level winds.
Just one of many notable storms in the 1930s, the storm of 9.-11. May 1934 began in the far north-western Great Plains and proceeded east over the northern tier of states and parts of Canada and was notable for removing the vast majority of the soil deposited since the last Ice Age over some parts of its path.
Another major dust bowl storm took place on April 14, 1935. It is known as Black Sunday
In June 2007, a large dust storm struck Karachi Pakistan and areas of the Sindh and lower Balochistan, followed by a series of heavy rainfalls which resulted in a death toll of nearly 200.

Mishe Vanatta:


Dust storms affected most of New South Wales and Victoria due to the below average rainfall during Winter and high winds.

Mishe Vanatta:
Dust Bowl

The Dust Bowl or the dirty thirties was a period of severe dust storms causing major ecological and agricultural damage to American and Canadian prairie lands from 1930 to 1936 (in some areas until 1940). It was caused by severe drought, coupled with decades of extensive farming without crop rotation or other techniques to prevent erosion, and the deep plowing of the virgin topsoil of the Great Plains, which killed the natural grasses. These grasses normally kept the soil in place and trapped the moisture even during periods of drought and high winds.

During the drought of the 1930s, with the grasses destroyed, the soil dried, turned to dust, and blew away eastwards and southwards in large dark clouds. At times the clouds blackened the sky, reaching all the way to East Coast cities such as New York and Washington, D.C. Much of the soil ended up deposited in the Atlantic Ocean. The Dust Bowl affected 100,000,000 acres (400,000 km2), centered on the panhandles of Texas and Oklahoma, and adjacent parts of New Mexico, Colorado, and Kansas.

The storms of the Dust Bowl were given names such as Black Blizzard and Black Roller because visibility was reduced to a few feet (around a meter). The Dust Bowl was an ecological and human disaster. It was caused by misuse of land and years of sustained drought. Millions of acres of farmland became useless, and hundreds of thousands of people were forced to leave their homes. Hundreds of thousands of families from the Dust Bowl (often known as "Okies", since so many came from Oklahoma) traveled to California and other states, where they found conditions little better than those they had left. Owning no land, many traveled from farm to farm picking fruit and other crops at starvation wages. John Steinbeck later wrote the classic Pulitzer Prize-winning novel The Grapes of Wrath and also Of Mice and Men about such people.

Navigation

[0] Message Index

[#] Next page

[*] Previous page