Summary: Instructional film about the importance of weather forecasting for pilots and aircrew with formation of weather types shown in graphical form.
Description: Reel 1:- The basis for modern day weather forecasting is the weather map and it is the main instrument of the weather forecaster. Pilots and aircrew should be able to understand the basic features of the weather map. Purpose of film is to study the features of the weather map. Weather readings taken at observing stations, temperature, cloud cover, rainfall measurements etc. Readings converted to internationally recognised code and sent to central HQ for forecasters. “The Weather Map” - constructing a weather map – reporting stations first added and elements shown e.g. Temperature, pressure, wind shown around station circle icon in preset positions. “Pressure Distribution” - two o'clock position, black ink, reading in tenths of millibars e.g 02.4 = 1002.4 millibars pressure at sea level. Isobars explained. “Temperature Distribution” - shown to top left of station circle icon and plotted in degrees Fahrenheit e.g. 50ºF. This information will reveal areas of warm or cold air. “Dew Point Distribution” - shown in red at bottom left of the station circle icon, and plotted in degrees Fahrenheit e.g. 48ºF. This provides information as to moisture in the air e.g. cold dry air and moist warm air areas. “Wind Distribution” - shown by line attached to station icon indicating direction and speed indicated by 'barbs' on the line. “Air Masses” - Polar Air and how the direction it moves into temperate regions (the UK) effects the weather e.g. “Maritime Polar Air” is air which has travelled over areas of ocean and therefore moist, “Continental Polar Air” has travelled over a landmass. Air from warm areas is called “Tropical Air” - Maritime and Continental Tropical Air described. Air Mass analysis is fundamental in modern forecasting.
Reel 2: - Explanation of formation of a “front”. “Depressions” - development of a depression shown. “The Warm Front” - section of a front in advance of a depression formed when warm air over takes cold air on a front – international symbol black semi circle on front line shown. “The Cold Front” - section of a front where cold air is overtaking warm air is called the cold front and international symbol is black triangle on front line shown. Direction of travel of front indicated by symbols being on leading edge of line. Warm Sector explained. Movement of warm air over cold air explained – formation of Cirrus cloud and Nimbostratus cloud formations shown. Changes in temperature, dew point, wind force and direction indicate approach of front and examples of reporting information symbols on station circle icons. Cold front undercutting warm front and effect on weather shown.
Reel 3:- ”Tendency” - Barometric Tendency explained – in advance of the warm front barometric tendency will be falling while in the rear of it the tendency will be falling then steady or falling less rapidly.Barometric tendency of cold front shown with accompanying symbols on station circle icon. Coalescence of cold and warm front shown – called an occlusion shown by a line with alternate black semi circle and triangle symbols – and the effect on weather shown. “Secondaries” - development of secondary disturbance around low explained. “Trough of low pressure” shown. Series of depressions shown developing along front. “Anticyclone” - development of anticyclone, which is an area of high pressure inclosed by isobars. “Ridge or Wedge of High Pressure” - outward extension of anticyclone is called ridge or wedge of high pressure. “Col” - region between two anticyclones and two areas of low pressure is called a “Col” explained.
Alternative Title:
Colour:B&W
Digitised:Yes
Object_Number:AMY 242
Sound:None
Access Conditions:
Featured Period:1946-1975
Production Date:1952
Production Country: GB
Production Details: AIR MINISTRY (Production sponsor)
Science Films (Production company)
