Given the task definition and input, reply with output. This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.

Passage: The primary source of rain in the Sahara is the equatorial low a continuous belt of low-pressure systems near the equator which bring the brief, short and irregular rainy season to the Sahel and the southern Sahara. The Sahara doesn't lack precipitation because of a lack of moisture, but due to the lack of a precipitation-generating mechanism. Rainfall in this giant desert has to overcome the physical and atmospheric barriers that normally prevent the production of precipitation. The harsh climate of the Sahara is characterized by extremely low, unreliable, highly erratic rainfall; extremely high sunshine duration values; high temperatures year-round; negligible rates of relative humidity, a significant diurnal temperature variation and extremely high levels of potential evaporation which are the highest recorded worldwide.
Where is the low-pressure that stops rainfall in the Shara?