A few yards in diameter, sway branches, kick up dust etc.
Last only a few minutes or less
1 to about 50 miles in diameter, sea breeze, mountain & valley breezes, thunderstorms
Lasts several hours to a day
The size of a normal High or Low, weather map scale
Lasts for days sometimes weeks
Planetary (global) scale
Circle the globe
A term that combines the synoptic and global scales together
Mesoscale winds or local winds are usually effected mostly by pressure gradient force
Due to their smaller scale, Coriolis has little effect on their motion
Remember our Coriolis Cub example of 100 miles 1,500 feet
The FAA includes the following as local winds
Mountain-plains wind circulation
All of these winds have a common driving force of surface heating and cooling
LAND AND SEA BREEZES
Day – sea breeze (from sea to land)
Warm land, cool water
Night – land breeze (from land to sea)
Cool land, warm water
The key concept here is that these winds depend on temperature differential to exist
Thus, the sea breeze will be stronger all things being equal
SEA BREEZE FRONT
At the leading edge of the cooler moister marine air, cumulus clouds may form if unstable air exists
If stable air exists, stratiform clouds may form
A peninsula, like Florida or an island is the perfect setup for this type of phenomena
Convergence of airflow from 2 directions enhance the upward lift
SEA BREEZES CAN BE DANGEROUS
Lawrence “Larry” Richard Walters (April 19, 1949 – October 6, 1993), nicknamed “Lawnchair Larry” or the “Lawn Chair Pilot“, was an American truck driver who took flight on July 2, 1982, in a homemade airship. Dubbed Inspiration I, the “flying machine” consisting of an ordinary patio chair with 45 helium-filled weather balloons attached to it.
Walters rose to an altitude of over 15,000 feet (4,600 m) and floated from his point of origin in San Pedro, California, into controlled airspace near Los Angeles International Airport.
In mid-1982, Walters and his girlfriend, Carol Van Deusen, purchased 45 eight-foot weather balloons and obtained helium tanks from California Toy Time Balloons. They used a forged requisition from his employer, FilmFair Studios, saying the balloons were for a television commercial.
Walters attached the balloons to his lawn chair, filled them with helium, put on a parachute, and strapped himself into the chair in the backyard of a home at 1633 W. 7th St. in San Pedro.
He took his pellet gun, a CB radio, sandwiches, beer, and a camera
When his friends cut the cord that tied his lawn chair to his Jeep, Walters’s lawn chair rose rapidly to a height of about 16,000 feet and was spotted by two commercial airlines.
At first, he did not dare shoot any balloons, fearing that he might unbalance the load and cause himself to spill out.
He slowly drifted over Long Beach and crossed the primary approach corridor of Long Beach Airport.
He was in contact with REACT, a Citizen band radio monitoring organization, who recorded their conversation:
REACT: What information do you wish me to tell the airport at this time as to your location and your difficulty?
Larry: Ah, the difficulty is, ah, this was an unauthorized balloon launch, and, uh, I know I’m in a federal airspace, and, uh, I’m sure my ground crew has alerted the proper authority. But, uh, just call them and tell them I’m okay.
After 45 minutes in the sky, he shot several balloons, and then accidentally dropped his pellet gun overboard. He descended slowly, until the balloons’ dangling cables got caught in a power line, causing a 20-minute electricity blackout in a Long Beach neighborhood.
Walters was able to climb to the ground.
He was immediately arrested by waiting members of the Long Beach Police Department.
Regional safety inspector Neal Savoy was reported to have said, “We know he broke some part of the Federal Aviation Act, and as soon as we decide which part it is, some type of charge will be filed. If he had a pilot’s license, we’d suspend that. But he doesn’t.”
Walters initially was fined $4,000 for violations under U.S. Federal Aviation Regulations, including operating an aircraft within an airport traffic area “without establishing and maintaining two-way communications with the control tower.”
Walters appealed, and the fine was reduced to $1,500. A charge of operating a “civil aircraft for which there is not currently in effect an airworthiness certificate” was dropped, as it was not applicable to his class of aircraft.
This process is similar to a sea breeze
Usually occur during summer
They have the best chance of forming in light synoptic wind conditions
They can be strong enough to cause thunderstorm formation
The deeper the lake the larger the temperature differential and the stronger the wind
Most prevalent around the Great Lakes but may occur around any large lake like the Great Salt Lake
MOUNTAIN AND VALLEY WINDS
The slope warms during the day warming the air causing it to rise.
The slope cools at night cooling the air causing it to sink.
Diurnal – change of temperature from day to night
This happens east of the Rockies
It’s basically half of the valley breeze model
Since the mountain warms faster, warm air ascends along the slope causing cool air from the plains to rush toward the mountain range
Watch for cumuliform clouds and thunderstorms in the afternoon
Any wind blowing down an incline.
A perfect example is when the Columbia basin gets snow, causing cold air to form near the surface creating an artificial High
This pressure gradient then causes an easterly wind in the Columbia gorge down by Portland.
Another smaller scale example is the Waterville plateau into Ephrata
Even though the air warms through adiabatic compression it is not enough to offset the temp differential.
These winds have been known to reach hurricane speeds in some parts of the world like the artic ice shelf area
Anabatic winds are winds that flow in the opposite direction (valley breeze)