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Posts tagged Sand Dunes

The “Empty Quarter” of the Arabian Peninsula

20.4N 45.7E

February 20th, 2013 Category: Deserts

Saudi Arabia – February 19th, 2013

The Rub’ al Khali or Empty Quarter is the largest sand desert in the world, encompassing most of the southern third of the Arabian Peninsula, including most of Saudi Arabia and areas of Oman, the United Arab Emirates, and Yemen. The desert covers some 650,000 square kilometres (250,000 sq mi).

The desert is 1,000 kilometres (620 mi) long, and 500 kilometres (310 mi) wide. Its surface elevation varies from 800 metres (2,600 ft) in the southwest to around sea level in the northeast. The terrain is covered with sand dunes with heights up to 250 metres (820 ft), interspersed with gravel and gypsum plains.

The sand is a usually reddish-orange color in some areas due to the presence of feldspar. However, here, its sands appear bright whitish tan in color here due to the infrared bands of the sensor used to capture the image. There are also brackish salt flats in some areas, such as the Umm al Samim area on the desert’s eastern edge.

Fields of Sand Dunes Along Coast of Northeast Brazil

2.8S 40.5W

February 18th, 2013 Category: Deserts

Brazil – January 19th, 2013

The northeast of Brazil (known locally as the Nordeste region) is characterized by semi dessertic weather and characteristics such as hot and dry temperatures, drought, lack of or scant rainfall, eroded soil and high evapotranspiration. Many coastal areas in region are covered by vast fields of active and stabilized coastal sand dunes.

Scientific studies show the vast prevalence of active sand dunes along the coast of NE Brazil in a tropical climate (average yearly rainfall above 1000 mm) results from the high powered trade winds, mostly during the dry season. Many stabilized dunes are found along this coast, side by side with the active dunes. A hysteresis model based on changes in wind power can explain the co-existence of stabilized and active dunes in the same area.

Vegetation on sand dunes in NE Brazil thrives when the rainfall is above 400 mm and the wind power is low. The dunes during the wetter periods were stabilized by vegetation due to low wind power and not because of the increased precipitation (click here for more information).

Lençóis Maranhenses National Park and Sediments Along Coast of Northeastern Brazil

2.7S 42.8W

October 9th, 2012 Category: Deserts

Brazil – October 8th, 2012

Sediments frame the coastline of northeastern Brazil, particularly along the states of Maranhão, Piauí, Ceará and Rio Grande do Norte (left to right).

Visible in the state of Maranhão, in the upper left quadrant, is the Lençóis Maranhenses National Park (Parque Nacional dos Lençóis Maranhenses), appearing as a large white area by the coast, just east of the Baía de São José. It is an area of low, flat, occasionally flooded land, overlaid with large, discrete sand dunes. It encompasses roughly 1500 square kilometers, and despite abundant rain, supports almost no vegetation.

Phytoplankton Bloom West of Namib Desert, Namibia – May 7th, 2012

24S 13.4E

May 7th, 2012 Category: Deserts, Image of the day, Phytoplankton

Namibia - May 6th, 2012

A faint phytoplankton bloom hangs in the waters off the shores of Namibia. The bloom is situated west of the southern part of the Namib Desert, an immense dunefield with tall, orange sand dunes. Phytoplankton blooms are common in this area due to the mixing of hot and cold ocean currents.

Bright Red and Orange Dunes of Southern Namib Desert, Namibia – May 1st, 2012

24S 14.9E

May 1st, 2012 Category: Deserts, Image of the day

Namibia - April 15th, 2012

This image focuses on the bright red and orange sand dunes of the souther Namib Desert. The Southern Namib (between Lüderitz and the Kuiseb River) comprises a vast dune sea with some of the tallest and most spectacular dunes of the world: in the Sossusvlei area, several dunes exceed 300 meters (984 ft) in height. As one moves eastward, the dunes give way to more rocky terrain.