Mystery Archive / Observation & interpretation
A cloud like a hovering saucer? Lenticular clouds and the air passing through
A saucer-shaped cloud can seem fixed while air keeps moving. Separate where the cloud forms from the air passing through that location.
First, what is a lenticular cloud?
A smooth saucer or stack of plates sometimes seems to hang in the sky. Lenticular clouds are one cloud form discussed in connection with such appearances. WMO’s atlas describes lens- or almond-like shapes, often associated with terrain but also possible where there is no marked terrain.
In a wave-like flow behind mountains, a cloud can appear stationary. Air keeps passing through: droplets form as it rises and cools, then evaporate as it descends and warms. The cloud’s location and the air’s movement are different questions.
This page does not ask you to identify a real cloud photograph. Move the same air marker through three positions on an assigned wave path beside a cloud region. Then compare sufficient- and insufficient-moisture assumptions while holding that path fixed.
First compare a moving air marker with a fixed cloud region. Then inspect a flow without a visible cloud.
Start with a name for a cloud’s shape
Lenticular describes a cloud form rather than an unfamiliar physical craft. WMO describes lens- or almond-like clouds that can be elongated and have distinct outlines. The form occurs in several cloud genera.
The name alone does not establish the air conditions at a photograph’s location. The familiar explanation of formation behind mountains should not be applied without exception to every lenticular cloud.
A cloud can stay in place without trapping the same air
The U.S. National Weather Service explains how relatively stable air crossing terrain can form waves, with cloud near their crests when moisture is sufficient. A crest is the high part of the up-and-down path.
UBC’s weather course connects rising, cooling air with cloud formation and descending, warming air with droplet evaporation. If that forming-and-evaporating region persists, air may pass through while the cloud seems to stay still.
The same cloud region, with air passing through
Hold the cloud region fixed. Compare the same air marker before entering it, near the crest and after leaving it.
Off · a marker outside cloud
On · small dots represent condensation
Off · a marker outside cloud
- Curved line: path followed by air
- Green-ringed circle: air we follow
- Blue region: where cloud forms
- Small dots inside the circle: cloud droplets
Sufficient moisture is assumed. These are three parcel positions under the same conditions, rather than three different clouds.
A 2003 Hawaii account separates wind from cloud movement
The National Weather Service’s Honolulu account describes persistent lenticular clouds over Hawaii’s Big Island on 25 November 2003. Flow around Mauna Loa and Mauna Kea produced waves, with cloud forming near their sufficiently moist crests.
The account explains that steady winds accompanied clouds that seemed almost motionless: cloud kept forming on the rising-air side and dissipating on the descending side. Our activity isolates a relationship rather than reconstructing that day’s measurements.
First comparison: move only the air marker
Move one green-ringed circle to before cloud entry, near the crest and after cloud exit. Mountain, wave path, wind direction and the sufficient-moisture assumption remain fixed. Does the blue cloud region follow the marker?
Small dots appear inside the circle near the crest and disappear after it leaves. They mark cloud droplets, rather than all water vapour turning into liquid and vanishing together. The cloud-forming region stays in the same place across all three choices.
- A Big Island lenticular-cloud case
The Honolulu weather-office account describes clouds forming and dissipating while seeming fixed as wind continued.
- WMO’s shape classification
The International Cloud Atlas describes lens- or almond-like forms, including occurrence without marked terrain.
- Moving air and cloud location
Weather-office and university materials connect rising and descending air with droplet formation and evaporation.
Second comparison: change only the moisture assumption
Now fix the marker near the crest. Try sufficient moisture for cloud formation and insufficient moisture in this flow. Check whether the blue cloud region appears or disappears while the wave path remains.
The National Weather Service notes that waves can be present when air is too dry for cloud formation. Our two assumptions separate that relationship; they are not predictions calculated from a measured humidity.
Separate a stationary appearance from verified conditions
This diagram assigns its wave path and cloud region. It calculates no real outline, size, stacked layers, temperature or wind speed. The air marker’s three positions do not represent measured time intervals.
A saucer-like appearance alone establishes neither a stationary craft nor that every unidentified sighting was a lenticular cloud. Location, successive observations and the air conditions would provide additional evidence for an explanation.
Follow air through a cloud that seems to stay still
Separate moving air from where cloud forms, then compare a case with no displayed cloud in the same flow.
Compare moving air with cloud locationSources and scope
WMO’s classification defines the scope of the name. National Weather Service explanations, its 2003 case account and UBC’s teaching material distinguish moving air from the region where cloud forms.
- 01Lenticularis · International Cloud Atlas World Meteorological Organization · 2017 edition · Checked 2026-10-22
- 02Altocumulus Standing Lenticular Clouds NOAA · National Weather Service, Albuquerque · Checked 2026-10-22
- 03ATSC 113 · Special Clouds: Lenticular Clouds University of British Columbia · Earth, Ocean and Atmospheric Sciences · Checked 2026-10-22
- 04Lenticular Clouds · Big Island, November 25, 2003 NOAA · National Weather Service, Honolulu · Checked 2026-10-22
The prose and explanatory diagrams are original. No cloud photograph, satellite image, institutional diagram, scan or logo is reproduced or traced. The assigned curve and cloud region explain a relationship; they calculate no real temperature, humidity, wind, height, time or droplet count and do not diagnose an image.