Parts of the Sahara desert are turning dramatically greener than normal as a result of an unusual shift in weather patterns.
With an area of 9,200,000 square kilometres, the Sahara is the largest hot desert in the world and the third-largest overall. It covers 10 different countries — Algeria, Chad, Egypt, Libya, Mali, Mauritania, Niger, Western Sahara, Sudan, and Tunisia.
The average annual temperature is 30C, although the mercury is recorded to have previously gone as high as 58C.
The area receives little rainfall – in fact, half of the Sahara Desert receives less than one inch of rain every year. However, the Sahara has been hit by freak thunderstorms that have resulted in torrential downpours.
At the same time the rain has penetrated further north than usual, resulting in the sprouting of vegetation in areas one would not expect.
NASA imagery shows the biggest increase in greenness occurring across the strip of north-central Africa covering southern Mauritania, southern Mali, Burkina Faso, southern Niger, northern Nigeria, southern Chad, southern Sudan, and portions of South Sudan, Eritrea, Ethiopia and Kenya.
The northward shift in greenness is the result of monsoon rains pushing further north than usual.
Portions of Mali, Niger, Chad, Sudan and Eritrea have seen the largest increases in rainfall compared with normal.
Some areas have received as much rain in the past month as would typically fall in a half-year or more.
The unusual weather has been caused by the Intertropical Convergence Zone (ITCZ) moving further north than normal.
The ITCZ appears as a band of clouds, usually thunderstorms, that encircle the globe near the Equator.
In the Northern Hemisphere, the trade winds move in a southwestward direction from the northeast, while in the Southern Hemisphere, they move northwestward from the southeast.
The location of the ITCZ gradually varies with the seasons, roughly corresponding with the location of the thermal equator.
