H
Clumps of layered ice that form in updraughts (rising air) within thunderstorms.
For terms describing hail in forecasts see Intensity of hail, Giant hail and Large hail.
Extremely small dry particles suspended in the air that reduce horizontal visibility, like light mist. Haze is distinguished from mist by humidity. If the humidity is less than 90%, it's haze.
Three or more days in a row when both daytime and night-time temperatures are unusually high. Temperatures must be high compared to the local long-term climate and the recent past.
Atmospheric circulations of high air pressure that rotate anticlockwise in the southern hemisphere. High pressure systems generally bring lighter winds and fine, settled conditions.
The ocean areas for which the Bureau provides forecasts and warnings. These are part of the Global Maritime Distress Safety System.
See lunitidal interval.
The highest level of water which can be predicted to occur under average meteorological conditions and any combination of astronomical conditions.
Highest tide level predicted under average meteorological conditions and any possible combination of astronomical conditions. Often referred to as HAT.
The Water Regulations 2008 outline 2 types of water information – historical information, and new or ongoing information.
Historical information is information a person holds before the end of the grace period.
Regulation 7.04 lists certain subcategories of water information and person categories. An organisation listed in these person categories and holding these data during the grace period gives them as historical information. They give historical information within a fortnight after the end of the grace period.
A deposit of interlocking ice crystals formed by direct deposition on objects such as tree branches, leaf edges, wires and poles.
Measure of how much water vapour is in the air.
Large-scale severe storm with violent winds. This term is used in the USA. In Australia, these storms are called tropical cyclones and in Asia, typhoons.
Area of science concerned with the distribution, properties and movement of Earth's water.
Study of atmospheric processes that affect water resources. This includes the atmospheric and land phases of the hydrological cycle and the relationships involved.