cirrus clouds
... that cirrus clouds cover an average of 20% to 25% of the Earth's surface at any time and can produce glories, fire rainbows, and sundogs?
... that <b id="mwFko"><a href="./Cirrus_cloud" id="mwFks" rel="mw:WikiLink" title="Cirrus cloud">cirrus clouds</a></b> <i id="mwFkw">(pictured with a fire rainbow)</i> cover an average of 20% to 25% of the Earth's surface at any time and can produce <a href="./Glory_(optical_phenomenon)" id="mwFk0" rel="mw:WikiLink" title="Glory (optical phenomenon)">glories</a>, <a href="./Circumhorizontal_arc" id="mwFk4" rel="mw:WikiLink" title="Circumhorizontal arc">fire rainbows</a>, and <a href="./Sun_dog" id="mwFk8" rel="mw:WikiLink" title="Sun dog">sundogs</a>?