photo #4372732

When the low individual masses of cloud known as Cumulus line up in rows, we call them cloud streets. This arrangement happens when the thermals on which the clouds form – the columns of air that rise off the Sun-warmed ground – arrange themselves into lines aligned to the direction of the wind. These streets of cloud when viewed from below appear to emanate from a point in the distance due to the effect of perspective. This is why the formal name for this formation is Cumulus radiatus. Emily Giles (Cloud Appreciation Society Member 59,636) spotted these Cumulus radiatus while flying over northern Morocco. From her elevated position, they didn’t have the fanned-out appearance that they would have from the desert below. Emily’s view shows that the streets of Cumulus aligned to the winds that we call radiatus are, in fact, completely parallel.