Glossary — weather

Beaufort, sea state, fronts, tropical systems, squalls, ice.

19 terms in this category.

• Anemometer
  An instrument for measuring wind speed, with the cup anemometer and sonic anemometer being the most common types aboard ships.
• Backing
  An anti-clockwise shift in wind direction in the Northern Hemisphere, often indicating the approach of a low pressure system or cold front.
• Beaufort Scale
  An empirical scale from 0 to 12 that relates wind speed to observed sea surface conditions and wave heights.
• Cumulonimbus (CB)
  A deep, vertically developed convective storm cloud extending to the tropopause, producing squalls, lightning, heavy rain, and microbursts.
• Doppler Weather Radar
  Ship-borne or shore-based weather radar that uses Doppler shift to estimate precipitation intensity and storm motion.
• Freezing Spray
  Sea spray that freezes on contact with vessel surfaces in sub-zero air temperatures, causing rapid topside ice accretion and raising capsize risk.
• Hurricane
  A tropical cyclone in the Atlantic or eastern Pacific with sustained winds of 64 knots or more on the Beaufort scale.
• Inter-Tropical Convergence Zone (ITCZ)
  A belt of converging trade winds near the thermal equator characterised by squalls, doldrums, and heavy rain, migrating seasonally with solar heating.
• Intertropical Convergence Zone (ITCZ)
  A band of low pressure near the equator where trade winds converge, producing persistent convective weather and squalls.
• Lapse Rate
  The rate at which atmospheric temperature decreases with increasing altitude, averaging approximately 6.5°C per kilometre in the standard atmosphere.
• Monsoon
  A seasonal reversal of prevailing winds affecting the Indian Ocean and western Pacific, bringing heavy rainfall on its wet phase.
• Rogue Wave (extreme wave)
  Wave more than ~2× the significant wave height; rare but documented and dangerous.
• Sea Fog
  Advection fog formed when warm, moist air moves over a cooler sea surface, reducing visibility to less than 1,000 metres.
• Sea State
  A description of wave conditions at a given location, typically expressed by significant wave height and period.
• Significant Wave Height (Hs)
  Statistical measure of sea state: average height of the highest one-third of waves observed.
• Squall
  A sudden, brief and intense increase in wind speed often accompanied by rain or hail, posing an immediate hazard to vessels.
• Swell
  Long-period regular waves that have travelled out of the generating area, independent of current local wind conditions.
• Typhoon
  A tropical cyclone of the western North Pacific with sustained winds exceeding 64 knots, the regional name for a hurricane.
• Veering
  A clockwise shift in wind direction in the Northern Hemisphere, typically associated with the passage of a warm front.