photo #5630134

The highest of the ten main cloud types, Cirrus clouds are composed entirely of ice crystals. Sometimes, high-altitude winds can draw these streaked clouds out into long, parallel fibres, which are referred to as Cirrus fibratus. Other times, Cirrus can appear more twisted, like those in some parts of this sky spotted by Pavel Bonder (Cloud Appreciation Society Member 62,502) over Tel Aviv, Israel. Such patches would be classed instead as Cirrus intortus, from the Latin word for ‘twisted’ or ‘tangled’. They form where the winds vary arbitrarily with altitude – or, if you prefer, where this high cloud prefers not to be combed out straight.