Education Time from you to me to the AMC!
2018-09-02 17:06:16.000 – Zach Butler, Summit Intern
I have always been passionate about the education around meteorology. The science affects people’s lives every day, every hour, and every minute. The importance of educating the public on this science is vital for communities to understand the dangers and aesthetic around meteorology.
Every day, we at the Mount Washington Observatory, radio our morning weather conditions and 48hr forecast to the Appalachian Mountain Club (AMC) huts and shelters. The staff writes and posts are forecasts for themselves and people traveling through to see and take note. The importance of these forecasts are vital for the outdoor community in the White Mountains to understand the weather conditions they will be facing. As an AMC member on a trail crew the past two summers, I have a personal relationship and communication within the AMC. Friends and family have always asked me about the weather in all forms of questions. The biggest impact I took from these interactions was what are all these terms you use? These “terms” were common knowledge to me as a meteorologist. However, many people did not understand these definitions or terms we as meteorologists use.
As an intern on Mount Washington this summer and now through the fall, I have taken even more interest in the education surrounding meteorology. This last week, I have begun to develop a glossary of common meteorologist terms we use at the observatory in our forecasts. The goal is to share this information with the AMC to help them and the outdoor community understand what the heck us meteorologists are actually saying. This glossary is 2 pages and has several diagrams that explain and describe common weather terms and physics. I’ll comment some examples of meteorology terms that I have written into this glossary:
Relative Humidity (RH) – amount of moisture in the atmosphere that is dependent on the temperature. Used in a percent (%)
Barometric Pressure – the weight of the atmosphere, measured in inches of mercury (Hg) or millibars (mb)
Rising pressure – clearer weather on the way!
Falling pressure – unsettled weather on the way!
Pressure gradient – the decrease in pressure per unit of horizontal distance
Tight gradient – associated with low pressure and higher winds
Loose gradient – associated with high pressure and weaker winds
Jet Stream – atmospheric river of higher winds that steers all weather systems. Can occur at multiple levels in the atmosphere (low-level, mid-level, upper level jet. See level’s below)
*These are simplified diagrams. Real scenarios are often different, but this gives a good idea of what they look like!
Trough – A horseshoe area of lower pressure created by the jet stream
Ridge – An upside down horseshoe area of higher pressure created by the jet stream
Long Wave Trough – a pressure trough characterized by large length and usually long duration
Short Wave Trough – a pressure trough characterized by small length and a shorter duration. Often leads to upward motion and lift ahead of it
What makes a thunderstorm?
Instability (Unstable) – the tendency for air parcels to accelerate from their original position (usually upwards!)
Moisture – water vapor content in the atmosphere. Need high dew points or high RH
Lift – the vertical movement of air or a fluid
Convection – vertical transport of heat and moisture by movement of a fluid (air)
Hail – ice particles observed from some thunderstorms. Only occurs in summer!
Sleet – not in a thunderstorm! Ice particles observed when the surface is below freezing
Levels of the atmosphere:
Low-levels – lowest 700mb of the atmosphere
Mid-levels – between 700mb and 500mb
Upper-levels – 500mb and higher of the atmosphere
Diurnal Variability – variability of any variable (temperature) from day to day or night
Subsidence – a descending motion of air in the atmosphere
Stable – lack of vertical motion. Warm air above cold air inhibiting vertical movement
Inversion – temperature increases with height
Heat index – how hot it really feels when the RH is added to the temperature
How do the mountains make or create weather?
Upslope or Topographic lift – air is forced upward and creates clouds or precipitation; dependent on wind direction Lapse Rate – temperature decreases with height on average 3-5 degrees F with every 1000ft. The drier the air, the cooler air colder as you increase height
*This is highly variable (Dependent on moisture in the air)
This is what I’ve developed this week, minus the diagrams. These terms were developed based on what we use in our current summit conditions, as well as our forecast discussions. I hope these terms are understandable and relate some of the science of meteorology to understandable terms. Well that’s all the time I got, I’ll sign off with a beautiful sunset we had this week on the summit. Have a great day!
Zach Butler, Summit Intern