Radio-sonde balloon being released. Beneath the balloon
 is the target which can be tracked by radar, 
while the transmitter is being held in the hand

first operation in which H.M. Ships, particularly frigates, have been required to carry out observations on so large a scale. Meteorological reconnaissance aircraft will make both high and low level flights with full observational reports. Canberra P.R.7 aircraft will fly at about 45,000 feet making observations of cloud, temperature and wind observations measured by a very special instrument. Shackleton aircraft make the low level sorties, making similar observations. Ships and shore stations are able to make observations to great heights, while aircraft are able to make observations over a great area; daily sorties of about 2,000 miles will be made. Data from other stations, Honolulu, Fiji Islands, etc., will be received by wireless. At H.Q. will also be the safety officers and all information from ships and shore stations will be received at H.Q. and passed to them for their most important task.
      As we ascend in the atmosphere from the earth's surface, the' pressure always falls off at an almost constant rate. Temperature variations are much more complicated. Temperature usually decreases as height increases and if it decreases very rapidly then rain clouds and radio-active