Vincent J. Schaefer

Surface Replicas for Use in the Electron Microscope

A simple method is described for making replicas of surfaces for study in the electron microscope. The surface to be studied is cleaned and then coated with a very thin slightly wedge‐shaped film of polyvinyl formal having a range in thickness from about 500 to 750A in 2.5 cm. This film is formed by dipping the prepared surface into a 0.5‐percent solution of the resin dissolved in dioxane or ethylene dichloride and permitting the solvent to evaporate while the surface is held in a vertical position. The replica film is removed by placing the coated surface under water and peeling the film from it. A description of this technique is given in detail. A graph is presented which shows the thickness of resin films obtainable from various concentrations of resin in dioxane, and a table gives the interference effects which may be used for determining approximate thicknesses of thin resin films. Several easy procedures are described for checking the thickness of such films. A technique is described for preparing ...

The Production of Clouds Containing Supercooled Water Droplets or Ice Crystals Under Laboratory Conditions

The basic laboratory experiment in which a supercooled cloud may be seeded and converted to ice crystals is described in considerable detail. Such information is given as type and preparation of th...

Snow and its Relationship to Experimental Meteorology

Snow in its many forms has been the subject of observation, conjecture, and scientific discussion for many centuries. It has long been recognized that a better understanding of the formation of snow in the atmosphere would eventually explain some of the little-known but important meteorological processes related to the development of precipitation.

Cloud Forms of the Jet Stream

A combination of four cloud types including specific forms of cirrus, cirrocumulus and altocumulus have been successfully correlated with the reported location of the major axis of the jet stream. Recognition of these cloud patterns from the ground may prove to be a simple method for locating the high velocity component of the jet. Field observations of these spectacular clouds have been made at various parts of the United States. More than 500 feet of time-lapse motion pictures have been obtained of such clouds and show remarkable high velocity, shear, turbulence and waves which typify portions of this high velocity stream of air. These cloud structures display the coherency and the high rate of motion which would be expected of the jet stream. Preliminary studies have indicated that the proximity of the major axis of the jet stream sometimes modifies air motions at low altitude and may be responsible for excessive winds on mountain summits and anomalies of forest fire behavior. Detailed studies by time-lapse photography should establish more of the physical properties of this important component of the atmosphere. DOI: 10.1111/j.2153-3490.1953.tb01032.x

Atmospheric Studies from a Moving Weather Observatory

An exploration of the diurnal variations in the microclimate of a forested mountain in northern Idaho was made during a 36 hour period toward the end of a prolonged period of cloudless weather. Measurements were made from the mobile weather observatory developed jointly by the University of Washington, U. S. Forest Service and the Munitalp Foundation. A 4 meter mast mounted so it rode six feet ahead of the vehicle contained sensing elements at the ½, 2 and 3½ meter positions. Temperature and dew point were recorded on an eight channel recorder which completed its cycle every 32 seconds. Exploratory runs were made during which the observatory stopped at each 500 foot gain in altitude and at several additional stations in between. A study of the data showed, however, that the response time of the aspirated temperature and dew point sensing elements was so rapid that pauses were not necessary if the vehicle moved in the speed range of 6 to 10 mph. Large differences were noted between day and night and north ...