The Free Lift of Spring

I was flying home to Michigan after all the thunderstorm and tornado excitement of Sun ’n Fun. If there has ever been a major air show with worse and more severe weather than Sun ’n Fun this year, I can’t remember it. It’s just amazing that the loss of airplanes wasn’t greater, and that nobody was seriously injured.

But for my trip home the severe weather, thunderstorms, and springtime snow blast had moved up the East Coast, leaving a windy high pressure system in its wake. High pressure usually means good flying weather in terms of good visibility and absence of low cloud cover, but it can also be among the most miserable flying conditions ever. This was one of those miserable days because the air was so unstable. You can find unstable air anytime of the year, but in the spring, it is more common, and the degree of instability can be extreme.

The mark of unstable air is cooling with altitude. The warmer air at the surface rushes up into the clear colder air aloft. When the rising air cools to the dew point a layer of clouds – usually scattered or broken – will form. Depending on how much moisture is in the air, these clouds are often small cumulonimbus with the tops often stretching up to touch the freezing level.

When a strong instability exists you can bet your house on one thing – turbulence. The rising air is enough to disturb an airplane in flight. The parcels of air do not rise at a uniform rate so there are bumps when you transition from one lifting air current into another. But the real culprit is the wind.

As the wind blows through the rising currents of air it jumbles the air mass into a big turbulent mess. Visualize how a fast moving stream of water reacts when it encounters a rock in the stream and you can imagine how the air molecules are behaving when a strong wind blows through a rising mass of air.

The bad news is that the spring is also a season of sharp contrast between areas of high and low pressure, and of temperature extremes. That means strong winds are common. Blow a strong wind through an unstable air mass and you have hit your head on the ceiling turbulence. And that’s what I had to fly through most of the way from Florida to Michigan.

Clouds are often more turbulent than the clear air because it is the rapidly moving and cooling of the air that helps to form a cloud. But in a springtime unstable air mass the bumps can be almost as bad in the clear air.

However, there is usually smoother air above the tops of the clouds, if you can get there. The cloud tops typically mark a change in air temperature and indicate where the air has slowed its rise. With a more stable layer above the clouds, wind is the main turbulence producer, so if you can find a spot between layers of wind shear, there is a smooth ride.

But altitude alone does not guarantee a smooth ride. On this day there were plenty of complaints from jet crews flying above 30,000 feet. Sometimes the air gets stirred up by the contrasts of temperature and pressure all the way up.

There is, however, one advantage of flying through a springtime unstable air mass: free lift. The rising air pushes the airplane up and to hold altitude you have to put the nose down, so airspeed increases. On this day my cruise speed was averaging 15 knots faster than normal.

The only problem was that a few times I had to pull the power back because the indicated airspeed was close to the yellow arc and I didn’t want to fly into that yellow airspeed zone that is reserved for smooth air only. In the spring these areas of rising air can go on for many, even hundreds of miles. I guess at some point the rising air comes back down, but not along my route that day.

On a brilliant spring day with a bright blue sky filled with scattered puffy white clouds after the bad weather has moved on, a non-pilot looks up and says, “What a great day to go flying.” Little do they know what the air is really doing on a day like that. But we do.

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10 Responses to The Free Lift of Spring

  1. Jeff says:

    I have tried my best to get a handle on weather over the years, I don’t think I missed a column that Richard Collins wrote about weather, but despite my best efforts a good understanding of weather eludes me. Having said that I enjoyed your article, and yes it has been especially windy in southern Illiniois where I live

  2. mike kelley says:

    Hi Mac
    Yes spring time can be tough, Im based at PTK (Waterford MI) and I flew the other day just for some good crosswind take offs and landing. Winds were 330 at 18 with gust to 28. Guess what it was not only a gusty crosswind but plenty of bumps so we only flew for 30 mins or so. Oh the great time we have flying in Michigan in spring time! Safe skies my friends.

  3. Ed Aaron says:

    You have just described the ultimate soaring conditions. Bumps are not a problem and the smile usually never leaves your face. Try it!

  4. Linwood Stevenson says:

    Hi Mac,

    The old saying about one man’s trash is another’s treasure came to mind while reading the above column. I believe I was flying my glider the same day out of TN, and the lift was great, although somewhat turbulent. Managed to fly a 300+ kilometer triangle (almost 200 miles) during those conditions. It was a fantastic day to be in a sailplane, and managed a personal in state best climb up to 11,300′ msl after an earlier release from tow at about 2300′ msl (1500′ agl). Not bad for using no fuel and having no particular goal in mind… Much more relaxing than the old Boeings and Airbi formerly flown…

    Have enjoyed your columns over the years!

    • Mac says:

      You guys are so right about soaring conditions. I have flown gliders a few times and it is a blast. But I never lived in a part of the country where soaring conditions where good much of the year so I didn’t really take it up. But, in the spring, almost every part of the country has good soaring conitions on lots of days.
      Flying 200 miles mostly over Tennessee is really impressive.
      Mac Mc

  5. Greg Arnold says:

    Ditto for springtime flying in Colorado but here you can add to the mix strong west and south westerly jetstream winds rolling across the Rockies. Last week I got to do some turbulence induced aerobatics in my RV-7A on my way to practice aerobatics!

  6. Roger Halstead says:

    Last Thursday I flew the Deb just a short hop from IKW to MOP to get the tip tanks replaced along with new position lights and strobes. It was also a day like you describe. I could hear the sailplane pilots down by Ionia talking about the lift as I was bouncing my way merrily along at 3000 feet.

    Even with the light wing loading of the Debonair/Bonanza it handles the bumps pretty well, it’s unlikely this would have been a good day for a “first timers” ride. <:-)) I was gently reminded again as the wheels were just about to touch down when I felt and saw the presence of some unexpected lift which left as quickly as it arrived, depositing me unceremoniously in an "arrival" instead of a "greaser".

    I had made the common mistake of relaxing before the plane was parked.

  7. jim jacobs says:

    Hi Mac; This Sunday I will be flying from Tamiami to Great Barrington Ma. in my new Extra; I am hoping for a stratus layer to keep the bumps to a minimum with nice vis. The thing about the Extra is the high wing loading loves bumps; I wish I could say the same for my sorry body which really loves that smooth ride. Thanks for the blog; it makes my day.

  8. Rich says:

    A bumpy day in the cockpit beats a smooth ride at the desk any day!

  9. Jim Gombold says:

    One day flying from the East coast westbound, we tried every altitude from FL 180-FL-430, no change, constant chop. Lesson learned, sometimes you have to stay at altitude, save the fuel, and just ride it out.

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