Isobar maps are used by forecasters to analyse the current state of the atmosphere as a precursor to predicting future weather patterns. The display isobars, which are lines connecting points of equal atmospheric pressure, usually drawn at intervals of 4 millibars (5 millibars is more usual in continental Europe). Weather fronts are then added to indicate the bands of cloud and rain. Meteorologists at Met Éireann still hand-draw isobar maps because the kind of interpretation of data that is required is more accurately and efficiently performed by humans than by computers.
This exhibit contains reproductions of isobar drawings from the archives of the Met Éireann library, from three historicaly significant dates: 3–6th June 1944 (the decision to postpone D-Day), 15th September 1961 (Hurricane Debbie) and 11th June 1990 (Italia ‘90).
Met Éireann, the Irish National Meteorological Service, is a line division of the Department of the Environment, Community and Local Government. It is the leading provider of weather information and related services for Ireland.