At the beginning of last week, a large complex of thunderstorms, known as a mesoscale convective system developed east of Phoenix, Arizona.

The outflow of the MSC hit the ground and its winds of 50-60 mph lifted dust and sand into a thick, choking cloud that smothered the city. Visibility dropped to almost zero and the 50-mile wide dust cloud crossed the surrounding cities of Avondale, Tempe and Scottsdale.

A haboob is an intense sandstorm characterised by hot winds, and can be found in any arid region throughout the world.

They are features particularly of the deserts of Arabia and North Africa, though, and the name comes from the Arabic word habb meaning “wind” or “to blow”.

Haboobs are often associated with thunderstorms. As a thunderstorm grows the air within it rushes upwards, causing low pressure at the surface into which winds blow.

As the storm begins to release heavy precipitation, however, air rushes downwards in a vigorous downdraught, rushing out horizontally in a blast of wind as it hits the ground – a “gust front”.

This can pick up large amounts of dust or sand, and haboobs can move as dense walls sand, reaching heights of 900 metres.

In fact, fine particles of dust can even be carried thousands of kilometres into the atmosphere.

African haboobs are commonly observed during the summer months when moisture is brought from the Gulf of Guinea northwards, as a result of the northwards shift of the Inter Tropical Convergence Zone.

Haboobs can occur during the summer months in North America as well, particularly in the deserts of Arizona, New Mexico and Texas.