Reading Barometer Trends
The chart below is based on the last three hours of barometric pressure. Each hour it is either rising, sinking, or staying level and combinations of these form the slash graphics in red below. Thanks to David Wilkinson of the NW Maritime Center for these graphics and the presentation below.
Barometer Class Handout by D. Wilkinson.
Veering vs Backing
Veering is the same as “clocking around” in a clockwise direction. So a north wind veers to the northeast but backs to the northwest. Common usage says this is the same in the southern hemisphere.
Where is the Low Pressure Storm Center?
Buys-Ballots Law: With the wind at your back, low pressure will be to your left and forward ~ 20° (open water). “Wind Back, Low Left”. For the southern hemisphere it is reversed – with the wind to your back the low will be to your right.
Hurricane and Typhoons
Northern Hemisphere, winds move counter-clockwise. Right upper quadrant is the windiest.
Southern Hemisphere, winds move clockwise. Left upper quadrant is the windiest.