Weather Glossary - Z
Large-scale atmospheric flow in which the east-west component (i.e., latitudinal) is dominant. The accompanying meridional (north-south) component often is weaker than normal. Compare with meridional flow. Weather systems tend to move past quickly in a zonal flow regime.
Greenwich Mean Time (GMT). Centred on zero degrees longitude. For scientific purposes this time zone is also known as Universal Time (UTC). All meteorological observations worldwide are reported using this time (for ease of comparison and computation). This timezone is commonly suffixed with 'Z'.
Power is gradually being turned back on across parts of South Australia but much of the state remains in darkness after a widespread blackout.
South Australia and its 1.677 million residents were left without power on Wednesday evening following severe storms.
Federal Energy Minister Josh Frydenberg says serious questions will be raised about how the entirety of South Australia could be left without electricity in the wake of a huge storm, dubbed the largest in 50 years.