General Information

Serial #

N/A

Part Number

1

Total Parts

1

AKA

N/A

Patents

N/A

General Description

rubber?

Dimensions

Note: These reflect the general size for storage and are not necessarily representative of the object's true dimensions.

Length

18.5 cm

Width

6.5 cm

Height

N/A

Thickness

3.0 cm

Weight

N/A

Diameter

N/A

Volume

N/A

Lexicon

Group

Meteorology

Category

Cloud height & motion measurement

Sub-Category

N/A

Manufacturer

AKA

Unknown

Country

Unknown

State/Province

Unknown

City

Unknown

Context

Country

Canada

State/Province

Unknown

Period

at least 1950's to 1970's; this instrument was apparently in use for 20 years (Ref. 8)

Canada

A ceiling balloon of a type used by the Meteorological Service of Canada to gather cloud height data across Canada from at least the 1950's to the 1970's. A three inch ceiling balloon is listed in MSC's instrument inventory manuals of 1952, 1958 and 1961 (Ref. 5) and its use is described in both the 1955 and 1970 ceiling balloon equipment manuals (Refs. 2-3). Part of a large collection of meteorological instruments acquired from the Meteorological Service of Canada (previously Atmospheric Environment Service) by the CSTM since 1967. MSC is the government agency responsible for collecting and disseminating meteorological data and forecasts in Canada. It was founded in 1871 in Toronto where it is still headquartered. The MSC was originally on the University of Toronto downtown campus but moved to Downsview in 1971 on land owned by UofT. The headquarters houses laboratories, research facilities and calibration and instrument maintenance facilities (now largely contracted out).

Function

A small balloon used to determine the height of the cloud base. The height can be computed from the ascent velocity of the balloon and the time required for its disappearance into the cloud.

Technical

An example of a MSC 3 inch ceiling balloon. While inexperienced human observers can only estimate cloud heights to ±50%, extended experience with other observations such as pilot reports and ceilometers can be greatly reduce these human errors to probably ±20%. More accurate measurements of cloud height during the day are made with a 7.5 cm (3") helium or hydrogen filled balloons that rise at a near constant rate of 140 m/min. The observer records the time elapsed until the balloon disappears into the cloud deck. The observer fills the balloon on a filler stand (1987.0836) which is specifically weighted to give the correct free lift for 140 m/min. At night a powerful vertically pointing ceiling projector is used. An alidade (also called a clinometer, (1987.0736) is located usually 305 metres away from the projector. The observer adjusts the vertical angle of the alidade to the light spot formed on the cloud. The cloud height is read directly off the height scale on the alidade. The scale calibration depends upon the length of the baseline to the projector (Ref. 1).

Area Notes

Unknown

Details

Markings

none

Missing

complete

Finish

red

Decoration

N/A