Here is an example of perception confronted with reality at night, in conditions of fog and poor visibility. What happened at Theodore Francis Green Airport, in Warwick, Rhode Island, could have turned into a major disaster. Listen and watch the video:
SR71 Blackbird – USAF photo by Tech SGT Michael Haggerty – Source: www.af.mil
This unbelievable test flight happened in 1966, and remained top secret for decades given the constraints of the Cold war at that time. You can read this breath-taking story in browsing into Google. Type – SR-71 Blackbird breakup at Mach 3.18 – (or click on this link, then on the first webpage of the Google list proposed). Plant yourself firmly in an armchair, then you can start to read the most amazing aeronautical report I have ever read!
ELMENDORF AIR FORCE BASE, Alaska – Members of the 703rd Aircraft Maintenance Squadron de-ice a C-17 Globemaster III from the 517th Airlift Squadron before a training mission. Heavy snow and weeks of sub-zero temperatures require extra effort from maintenance crews to keep the aircraft clear of ice and snow. The training mission included dropping Army Airborne Soldiers from Fort Richardson, Alaska, and conducting air drops of training bundles that simulate the Soldier’s equipment. (from AIR FORCE LINK)
Dew does not actually fall; rather the moisture condenses from air that is in direct contact with the cool surface. During clear, still nights, vegetation often cools by radiation to a temperature at or below the dew point of the adjacent air. Moisture then collects on the leaves just as it does on a pitcher of ice water in a warm room. Heavy dew is often observed on grass and plants when there is none on the pavements or on large, solid objects. These objects absorb so much heat during the day or give up heat so slowly, they may not cool below the dew point of the surrounding air during the night. Another type of dew is white dew. White dew is a deposit of white, frozen dew drops. It first forms as liquid dew, then freezes.
Frost, or hoarfrost, is formed by the process of sublimation. It is a deposit of ice having a crystalline appearance and generally assumes the form of scales, needles, feathers, or fans. Hoarfrost is the solid equivalent of dew and should not be confused with white dew, which is dew frozen after it forms.