Starting with the post on August 27, 2025, any term that I use in the blog will be defined here.
- Airmass – An area of air characterized by a certain attribute, like humidity or temperature.
- Anticyclone – An alternate word for “high pressure system”.
- Atmosphere – The air encircling the globe.
- AQHI – Air Quality Health Index.
- AQI – Air Quality Index.
- Bermuda high – A high that always sits in the north Atlantic.
- Block – A shortened version of “Blocking system”.
- Blocking system – A collection of some amount of upper-level highs and lows that sit in one place for days and block other systems from moving through it.
- Cold snap – An alternate word for “cold wave”.
- Cold wave – A period of low temperatures.
- Cloud – An area of condensed water vapor in the atmosphere, appearing somewhere on the greyscale.
- Cloud cover – The amount of clouds visible
- Cyclone – An alternate word for “low pressure system”.
- Dew point – The temperature it would have to get to to create dew. A common myth is that the humidity is what controls how “humid” the air feels. That is incorrect; it is actually the dew point.
- Front – A moving line where one lower-level airmass changes to another.
- Frost – Water vapor that sublimates directly on to surfaces on cold nights.
- Haze – Non-significantly reduced visibility
- Heat wave – A period of high temperatures.
- High¹ – The highest temperature occurring in a day, usually 1-5 hours before sunset.
- High² – A shortened version of “high pressure system”.
- High pressure system – An area of higher pressure, also usually denoted by winds rotating clockwise outwards (in the northern hemisphere) and low amounts of cloud cover.
- Humidity – The moisture content of the air.
- Jet – A shortened version of “Jet stream”.
- Jet stream – One of 4 bands of moving air circling around the globe from west to east.
- Longwave – A ridge/trough accompanied by at least one upper-level high/low, that is creating a significant bulge in the jet stream.
- Low¹ – The lowest temperature occurring in a night, usually 0-3 hours before sunrise.
- Low² – A shortened version of “low pressure system”.
- Lower-level – Used for highs and lows when they can be see on surface analysis charts, thus being in the lower troposphere.
- Low pressure system – An area of higher pressure, also usually denoted by winds rotating counter-clockwise inwards (in the northern hemisphere), high amounts of cloud cover, and precipitation.
- Omega block – A blocking system where a high is flanked by two lows and the jet stream wraps in between.
- Pacific high – A high that always sits in the north Pacific.
- Polar jet stream – The main jet stream, which separates warm from cold air.
- Precipitation – Solid pieces or ice or liquid droplets of water falling from a cloud.
- Pressure – The amount force being applied to an object. In meteorology’s case, the ground.
- Rex block – A blocking systems where a high positions itself north of a low (in the northern hemisphere) and the jet stream wraps in between.
- Ridge – A line of higher pressure adjacent to areas of lower pressure.
- Shortwave – A ridge/through that is stemming from a longwave ridge/trough, and is less prominent.
- Smoke – Fine particulate matter generated by fires.
- Surface analysis chart – A chart that shows conditions near the surface including station measurements, pressure isolines, and positions of fronts.
- Temperature – How hot or cold the air is, or the measure of the amount of movement in particles. Depends on if you’re thinking about it scientifically or not.
- Troposphere – The layer of atmosphere where all* weather occurs, ranging from the surface to somewhere in the teens of kilometres, depending on where you are in the world and what season it is.
- Trough – A line of lower pressure adjacent to areas of higher pressure.
- Upper-level – A high or low that can be seen on upper air charts, thus being in the upper troposphere.
- Upper air chart – A chart that shows conditions high in the troposphere including the jet stream, ridges, and troughs.
- Visibility – How far objects can be viewed in the atmosphere.
- Weather model – A system that analyzes current conditions to then predict the future.
- Wind – Movement of air. You know what it is.
*Except aurora, noctilucent and nacreous clouds, and overshooting tops of Cumulonimbus clouds.