photo #4577071

Mediocris is the name for the medium-sized form of Cumulus, the low, individual masses of cloud that form on a sunny day. Named with the Latin for ‘keeping to the middle’, this form of Cumulus is bigger than the smallest Cumulus, known as Cumulus humilis, but not as big as the largest ones, Cumulus congestus. It’s just about right. Dr. Mary Richardson (Member 59,660) spotted her Cumulus mediocris over Moulsford, South Oxfordshire, England as she finished an evening swim in the River Thames. The haze in the low atmosphere rendered visible the cloud’s shadow to cause crepuscular rays, which appeared to radiate from the cloud due to the effect of perspective as the rays shone towards Mary. The cloud’s abundance of tiny droplets scattered the sunlight so much that its middle looked dark, because the sunlight was unable to penetrate, and its thinner edges looked bright, because some of the light was sent in Mary’s direction. It may be in the middle, but there’s nothing mediocre about a Cumulus mediocris