Pilot Weather Wisdom book

While sitting home under the siege of COVID-19, it was time to finish book#5, PILOT WEATHER WISDOM. By posting excerpts of the book for feedback, I hope to enhance things from your suggestions and experiences.

Do you know your scales?

Nope, not talking about music. Weather is categorized based on scales. Some refer to it as scales of motion. Weather is grouped according to its size, the horizontal distance it spans, and how long of a lifespan i.e. its duration. From largest to smallest these scales are: 1. global or planetary 2. synoptic 3. mesoscale and 4. microscale.


The global scale includes events that impact large areas of our earth and last for weeks or perhaps months such as the polar jet stream. It circumnavigates the globe influencing the polar and middle latitudes. Global scale includes semi-permanent weather features such as subtropical highs, trade winds, the ITCZ (Intertropical Convergence Zone), polar highs, prevailing westerlies and the infamous and nefarious polar vortex. The polar vortex infiltrated the Ontario region with snow, on Mother’s Day eve.


Next is the synoptic scale. Phenomena on the synoptic scale spans over hundreds of miles (1000s of kilometers) and last for many days. Mid-latitude cyclones, hurricanes, typhoons, tropical storms, air masses and fronts are examples of synoptic weather events. Synoptic is Greek for “seen together” which can mean an overview or general summary. For weather, the overview are weather maps! Those maps flashed up on TV is synoptic weather.


Mesoscale is third from the top typically lasting from an hour to a day and influence 10s to 100s of miles (10s to 100s of kilometers) of distance. Mesoscale includes thunderstorms, complexes of thunderstorms such as MCCs (Mesoscale Convective Complexes), squall lines, sea and land breezes and turbulence.


The last scale of motion is microscale. These events occur typically from minutes up to an hour and cover small distances such as less than 6 miles (10 kilometers). Microscale includes tornadoes, rainbows, convective updrafts and downdrafts.

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