WHY DOES THE WIND BLOW?
Written by: Brian Neudorff
If you're a parent maybe you've been asked that question by your children or maybe you have wondered that yourself. There are several factor, most of which work together to make the wind move from one place to another. One of the factors is heating from the sun. The sun will warm a spot making it warmer than the surrounding air causing it to rise, the colder air, which is heavier, fills in to replace the void left by the rising warm air. This is how we get our lake breeze in the spring and summer as the land warms more than the lake and the cooler air flows in off the lakes to replace the air that warmed and lifted upwards over land.
The rising and sinking of air also causes pressure difference, where air flows from high pressure to low pressure. These pressure difference is why we see wind when talking about storm systems like the one we will see Tuesday and Wednesday.
In school did you have make a topographic map? These are maps where you draw the different elevations using lines that represent one constant height. If you were to show a canyon or mountains with one of these maps you would see the lines of different elevations very close to each other showing a rapid change in elevation over a short distance. This is very similar to how meteorologist use a weather map to determine wind speed.
The above map is for Tuesday night, early Wednesday morning when a cold front is forecasted to cross the state. Notice the black lines that seem to circle around the storm. These lines are called isobars. Isobars are lines of equal pressure. Like the contours that showed the same elevation on a topographic map, isobars show us the change in pressure from low to high pressure. Like the topographic map the closer the pressure lines are to each other over a short distance that is where you have the steepest pressure gradient. A steep pressure gradient is where you will find the strongest wind speeds.
As the storm system over the Northern Plains strengthen and a cold front sweeps across the state Tuesday night into Wednesday we are going to see our winds increase. Bob mentioned this on Saturday, and it is possible we could have some wind watches as well as advisories for Tuesday into Wednesday. It will turn windy on Tuesday and I expect winds out of the south-southwest 10-20 mph possible 15-25 mph gusting to 30 mph. As the front moves through there will be strong winds associated with its passage. Winds high above the front will be range 70-80 mph and with a strong shower or storm the winds could translate down to the surface with speeds of 50 to 60 mph. If this holds true there could be the possibility of some wind damage Tuesday night/Wednesday morning.
Once the front passes the strongest of the winds should go with the front but we will remain windy on Wednesday with gust 30 to maybe 40 mph. We will have to watch the forecast closely over the next 24 to 48 hours.
Brian, I love your explanation about what causes wind. I just wanted to let you know that i'll be printing out copies of your post to include in a packet for my children's unit on weather.
ReplyDeleteThanks!
I've been hearing all over from experts that winter will come on strong early this year. Joe Bastardi believes that to be the case, as does Joseph D'Aleo and many other local mets. But based on at least the next two weeks ensembles, the cold air will make little strong impressions on our area. And now many are noting that the current pattern setting up is very similar to a classic strong la nina. That seems to contradict this strong and early winter for our area, then, as lows cutting well to our west and true arctic air staying WELL north into NW Canada. At least the first 10 days into November look to be a bust for any signs of real winter. So what's going on here? If it looks like a bust of a winter is upon us, i'd like to know so I can lower my snowfall expectations and overall winter standards this year.
ReplyDeleteThanks for your explanation of where wind comes from. I have a couple of follow up questions: 1.) what is / causes "pressure" that creates storms and nice weather? 2.) I have lived on or near Lake Ontario most of my life. It seems as though when the lake breeze kicks in, it almost always blows out of the NE. Why?
ReplyDeleteOne more thing - I really appreciate you guys taking the time to answer questions and post comments about the weather. This is above and beyond your call of duty. This weather blog is typically the second thing I check in my online daily routine, after Facebook. I almost always learn something new about weather and about weather in our area. Once again, thanks guys.