Nubian Pyramids, Sudan

Nubian Pyramids
photo © Wufei07

Less famous than the Egyptian pyramids but not less fascinating, those burial monuments belong to the ancient kingdom of Kush, a rival to Egyptian settled from 2500 BC in the Nubian Valley (modern Sudan) to AD 350, when the kingdom of Axum invaded and conquered the capital Meroë and ended the Kushite dominance.

Compared to the Egyptians, they are more recent (built a thousand years after), smaller (the highest is less than 30 meters, Giza’s is 139 meters), and with steeper sides. There are around 200 pyramids in the Nubian Valley, more than in Egypt.

Meroë, located 240 kilometers north of Khartoum, is the biggest and best-preserved sacred area, where 30 kings, eight queens, and three princes are buried.

Although relatively unknown (the last group of pyramids was discovered between 2009 and 2012), the Nubian pyramids are recognized as UNESCO World Heritage Site since 2011.

Mammatus Clouds

Mammatus Clouds
photo © Craig Lindsay – Mammatus clouds over Regina Saskatchewan

Mammatus clouds are striking cloud formations mostly composed of ice with unusual shape due to protrusions hanging from the bottom of the clouds, formed by sinking cold air.
They can extend for hundreds of kilometers and stay visible in the sky for up to a few hours, usually before or after a storm, bringing often rain, hail, or snow, depending on the temperature of the atmosphere.

They are usually associated with cumulonimbus, which is indicative of heavy storms, but they may also be formed from cirrus and altostratus clouds, or even volcanic ash clouds.

http://www.bbc.com/earth/story/20150716-nine-rare-and-beautiful-clouds