Atmosphere – The thin envelope of gases, water vapour, dust, and other airborne particles that surround the earth. Commonly referred to as the "air."
Barometer – An instrument used to measure atmospheric pressure.
Blizzard – Heavy snow or blowing snow accompanied by winds of at least 40 km/h.
Climate – The average daily or seasonal weather of a particular place or region.
Cloud – A mass of small liquid water droplets or ice crystals suspended in the air.
Cyclone – An area of closed, circular fluid motion rotating counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
Dew – Moisture that has condensed on objects near the ground.
Dew point – The temperature at which water vapour condenses to a liquid.
Drizzle – Precipitation consisting of very small droplets of water.
Fair – Weather condition in which clouds cover less than 40% of the sky, there are no extremes in temperature or wind, and there is no precipitation.
Fog – A cloud hovering close to the Earth's surface.
Front – The area in which two air masses come into contact.
Frost – A thin layer of ice crystals that form on the ground and other surfaces when water vapour condenses below 32 degrees Fahrenheit or 0 degrees Celsius.
Gust – A sudden, brief increase in wind speed.
Hail – Precipitation consisting of pellets of ice.
High pressure – An air mass associated with fair weather.
Humidity – The amount of water vapour in the air.
Hurricane – An intense storm that genesally forms over tropical regions. It brings heavy rain, strong winds, and powerful storm surges that can cause severe flooding.
Lightning – The visible discharge of electricity associated with a thunderstorm.
Low pressure – An air mass associated with storms.
Meteorology – The science that studies the weather.
Mostly cloudy – Condition when 70-30% of the sky is covered with clouds.
Mostly sunny – Condition when 10-30% of the sky is covered with clouds.
Overcast – Condition when 90% or more of the sky is covered with clouds.
Partly cloudy (or partly sunny) – Condition when 30-70% of the sky is covered with clouds.
Precipitation – Any form of water, including rain, drizzle, sleet, hail, or snow, that falls to the ground.
Rain – Precipitation consisting of droplets of water.
Sleet – Precipitation consisting of ice particles.
Smog – Fog mixed with particles of pollution.
Snow – Precipitation consisting of small ice crystals.
Sunny (or clear) – Condition when less than 10% of the sky is covered with clouds.
Temperature – Degree of hotness or coldness of the air.
Thunder – The sound caused by lightning heating air and causing it to rapidly expand.
Tornado – A violent whirlwind often accompanied by heavy rain, hail, thunder, and
Variably cloudy – Condition when cloudiness of the sky varies between 20-90%.
Weather – The condition of the atmosphere at a given time.
Wind – Moving air.