Hail - Precipitation in the form of lumps of ice, mainly associated with thunderstorms. Hail size usually ranges from that of a small pea to the size of cherries, but has been observed as large as oranges. Hail in Canada occurs most frequently during the summer when thunderstorm activity is at a peak. Extensive damage in the agricultural industry is caused each year by hailstorms.
Category: - Weather

Halo - In ages past, the huge rings or haloes around the sun or the moon were thought to portend everything from storms to great personal disasters. We now know that they are the optical result of the refraction of light from the sun or moon by ice crystals in the very high cloud (9,000 meters) called cirrus or cirrostratus.On occasion, only two bright spots on either side of the sun can be seen. These are known as sun dogs and are caused when the ice crystals occur in a certain uniform arrangement.
Category: - Weather

Halyard - The line used to raise and lower the sail.
Category: - Maritime

Harbor Dues - Various local charges against all seagoing vessels entering a harbor, to cover maintenance of channel depths, buoys, lights, etc. all harbors do not necessarily have this charge.
Category: - Maritime

Harbourmaster - A man in charge of a harbour, authorizing entry, and arranging for Pilots to guide vessels into difficult harbours, past underwater obstructions, etc.
Category: - Maritime

Hard Aground - A vessel which has gone aground and is incapable of refloating under her own power.
Category: - Maritime - Risk

Hatch - An opening, generally rectangular, in a ship's deck affording access into the compartment below.
Category: - Maritime

Hatch Battens - Flat bars which are wedged against hatch coamings to secure tarpaulins.
Category: - Maritime

Hatch Beam - A portable beam used to support wooden hatch covers.
Category: - Maritime

Hatchway - A large covered, usually rectangular opening in a ships deck for putting and removing cargo from under the deck.
Category: - Maritime

Hawse Pipe - Casting, or castings, through deck and side of ship at bow for passage of anchor chain.
Category: - Maritime

Hawser - Large strong rope used for towing purposes and for securing or mooring ships. Hawsers are now mostly made of steel.
Category: - Maritime

Hazard - Activity task, operation, tool or agent that is a significant source of personal physical risk and potential negative consequences
Category: - Risk

Haze - Fine dust or salt particles dispersed through a portion of the atmosphere which reduce visibility. Haze is distinguished from fog by its bluish or yellowish tinge.
Category: - Weather

Heave To - To stop a boat and maintain position (with some leeway) by balancing rudder and power to prevent forward movement, a boat stopped this way is "hove to"
Category: - Maritime

Heavy Rainfall Warning - Whenever 50 mm or more of rain is expected in a 24-hour period, a heavy rainfall warning is issued.
Category: - Risk - Weather

Heavy Snowfall Warning - A warning is issued when 15 cm of snow or more is expected in a 24-hour period. It may be issued for lesser amounts at the beginning or end of the snow season.
Category: - Risk - Weather

Heeling - The inclination of a vessel to one side.
Category: - Maritime - Risk

Helm - A tiller or a wheel generally installed on the bridge or wheelhouse of a ship to turn the rudder during manoeuvering and navigation. It is in fact the steering wheel of the ship.
Category: - Maritime

Helmsman - An able-bodied seamen entrusted with the steering of a vessel.
Category: - Maritime