Tag: Atmospheric convection

Do You Miss Buffalo?

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I was just on the phone with my dad. We talked about the weather a little. He’s in Milwaukee where it’s 29 with a wind chill of 22. My office window thermometer shows 72.

“Bet you’re glad you’re not in Buffalo,” he said.

I am.

766 Auburn Ave Google Maps

I lived here, at 766 Auburn Avenue (Google streetview link) in the third floor apartment. It was a beautiful one bedroom with no insulation and enough water pressure to take a shower if no one in the other two apartments was! During the summer we were woken by squirrel races on the roof.

Those who live in Buffalo do so by choice. Anyone who wanted to leave left a long time ago. There is a survivor spirit among the residents.

It is a really nice, liveable city. Real estate is very reasonable. Summers are magical. Winters are hellish.

Starting in mid-November a thick veil of low clouds descends upon the city. This is the beginning of the process that spawns Lake Effect snow. It’s convection, like bubbles in a pot of boiling water. It will remain mainly cloudy with a handful of exceptions until spring.

This time of year the Great Lakes are warm and the flow through the atmosphere cold. Warm air near the lake’s surface is drawn up, condensing as it cools. Clouds form, often dropping snow.

Lake Effect season begins suddenly. The start is when the potential for big storms is greatest… as we saw this past week. Once Lake Erie freezes the process shuts down.

Lake Ontario doesn’t freeze. Sorry Syracuse.

For a real Lake Effect event, winds must be aligned through the atmosphere often parallel to a lake’s longest dimension.

These storms are VERY localized. The physics involved in Lake Effect snow is very similar to summertime thunderstorm formation. In fact, sometimes thundersnow is part of a Lake Effect storm.

Think “thunderstorm downpour” of snow… except instead of moving on, the storm continues for hours or days relentlessly.

aurora

This graph is from East Aurora, NY. Under land use it’s marked, “Urban.” People live there. That’s over 30″ of snowpack with a water equivalent of 5″.

The edges of Lake Effect storms are well pronounced. You drive out of Lake Effect snow like you drive out of a summer thunderstorm. And these boundaries stay in place as long as the wind doesn’t shift.

No one can cope with this much snow. No one is equipped, even those areas that get as much as 200″ of snow a year!

“Yes, Dad. I’m glad I’m not in Buffalo.” But I don’t regret a day of living there.

Let’s Look At Clouds From Both Sides Now

If it looks like the clouds are boiling, just like a pot of water on the stove, it’s because the dynamics are very similar. Heat is being transferred upward through convection.

NWS EDD

We seldom get the big picture of what’s on the radar by just looking at the sky. Not today. Today is different in SoCal.

The atmosphere is unstable on the the other side of the Santa Ana Mountains, around 30 miles east of me. That’s where the radar (at the top of this entry) shows strong thunderstorms.

What’s striking in the time lapse below are the mid and upper levels of the clouds producing the storms. There are no clouds in the way blocking my view.

If it looks like the clouds are boiling, just like a pot of water on the stove, it’s because the dynamics are very similar. Heat is being transferred upward through convection.

The heavy rain and lightning bolts are out-of-sight behind the mountains. Here, I only see the signs. Everything is moving north and will soon be gone.

Things You Can Learn From Clouds

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I’m going to put on my science teacher hat for a moment. I saw something cool. You might enjoy understanding what’s going on.

An hour ago I propped my tablet against the bathroom window to take a timelapse movie of the clouds&#185. The sky was filled with beautiful puffy cumulus clouds. On a realtime basis they were majestic and seemed to hover in place.

Not so when sped up by a factor of 150 (that’s one shot every five seconds). Now the sky is turbulent. Roiling!

Gil Simmons, who I used to work with at Channel 8, calls these COW clouds. COW for “cold-over-warm.” I’ve also heard the effect called “self defeating sunshine.”

There’s a larger than normal vertical temperature gradient over SoCal today. Earlier this afternoon the temperature dropped almost 10&#176 Fahrenheit between 5,000 and 7,000 feet. That’s the cause for the clouds–the cold-over-warm.

Later tonight you’ll have to climb from 4,500 to 11,000 feet for that same drop.

Since warm air is more buoyant than cold, it rises and condenses forming clouds. This warm air moving toward the cold is called convection. It’s how heat moves when you put a pot of water on the stove.

If you look carefully at the very top of some of the lower clouds in my timelapse you’ll see the convection in action. The clouds grow upward looking very much like the bubbles of water rising in that hot pot of water!

If it looks like the clouds are moving multiple directions at once, you’re right.

There is wind shear overhead. As the clouds gain altitude they move from a southwesterly flow to northwesterly. It was even more pronounced earlier today. That shear adds to the convective cloud buildup. In fact wind shear is a major factor we look at when predicting severe storms.

Too much for one day? I’ll stop now.

The atmosphere is amazing when you watch it up close. There is so much going on and explanations within the laws of physics for all of it.

&#185 – Try as I might I can’t figure out how to keep the Nexus 7 camera from refocusing from time-to-time. That’s why the shot goes out-of-focus a few times.