Adam Clarke on Jonah 4:8

A vehement east wind - Which was of itself of a parching, withering nature; and the sun, in addition, made it intolerable. These winds are both scorching and suffocating in the East, for deserts of burning sand lay to the east or south-east; and the easterly winds often brought such a multitude of minute particles of sand on their wings, as to add greatly to the mischief. I believe these, and the sands they carry, are the cause of the ophthalmia which prevails so much both in Egypt and India.