Meteorologically known as altocumulus standing lenticularus appear at an altitude of 6000 meters (troposphere). Lenticular clouds are formed from strong wind flow over mountainous regions creating elliptical cloud formations which resemble the classical flying saucer or a fleet.
Image one from http://boingboing.net
One of the most common misidentifications appears to be images of local fauna. The photographer is usually unaware of the 'darting wild life' at the time the photo is taken. Only when the image is brought up onto a PC, does the photographer realise an unusual anomaly present. The anomaly appears as 'fuzzy' and elongated and depending on the distance sometimes appearing with an upper dome like feature. The effect is generally caused by insufficient shutter speed of the camera and the relative distance producing little or no other characteristics other than a dark blur.
Images two (a & b)
There is no wonder that the oval feature with an array of flashing lights displayed in the night sky can cause some suspicions. Blimps take off from smaller domestic airports (Camden and Bankstown airports in the Sydney metropolitan area).
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Appearance can range from a single circle to clusters of dried grass in circular patterns. However a closer examination offers a more prosaic explanation.
Commonly known as 'fairy Rings', these circles are a result of turf fungus and mostly
appear during prolonged rainy periods. Fine webbing can form among the affected areas
accompanied by tiny mite-
Images six (a & b)
This is a rare misidentification but has known to occur. Parhelia appear as a second or third sun in the sky but is more defined as a solar halo. The Sundog phenomenon develops among Cirriform clouds (commonly in winter) when sunlight refracts as it penetrates through ice crystals.
Lens Flare & digital aberrations
Lens flare is not a common form of misidentification but has occurred on occasions. Hard light (mostly direct sunlight or its reflections) reflects on the camera lens elements before reaching the digital camera sensor creating certain shapes. The shape of the anomalous form or forms in the image depends on the type of the lens diaphragm.
Another digital anomaly is what I call digital burning. This mostly appears in sunset shots as a hard distinguished hemispherical or elliptical white shape. Digital cameras have a tendency to abruptly overload to white without any graduation, unlike film cameras. This 'digital burning' commonly occurs with basic models.
If you have witnessed a UFO, report it!