What do beer and thunderstorms have in common?

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We all know that beer and flying don't mix. What you may not know is that the same thing that causes trouble for your beer also causes trouble for your flying.

If you're already a weather expert, this post may help you visualize some of the terms you already know in a different way. If you're not, have no fear: you're going to be ahead of the game because you'll understand more about some technical weather terms that you'll see on your private and/or instrument written exams than I did back when I took mine.

Those terms are "convection" and "latent heat of condensation". I made it all the way past my instrument knowledge exam without truly understanding what made convection work. I knew that it was an upward motion of a parcel of air, which was enough to bluff my way though the questions on thunderstorms, but I never could understand why a blob of air would just keep rising until it couldn't rise anymore.

The answer (and, like most things in meteorology, it's a general answer, not a 100% of the time answer) is contained in the concept of "latent heat of condensation". In this case, to keep things simple, let's look as "latent heat" as meaning "stored heat", which might make it easier to see what's happening.

In the spring of 2013, Dale Durran, a professor of atmospheric sciences at the University of Washington, studied how much of an effect the condensation that appears on the side of a beer can has on warming its contents. In this press release, he calculates that a sheen of condensation roughly the thickness of a human hair could warm the beer by 9 °F (5 °C) in only five minutes! That's a whole lot of energy in a small amount of moisture.

To see if those calculations are correct, Durran and his colleague Dargan Frierson performed some experiments, the results of which were published in this not-overly-technical and easily readable paper called Condensation, atmospheric motion, and cold beer. One of the important parts of the paper investigates how much of the heating is due to stored heat of condensation being released and how much is due to heat being transferred from the surrounding air.

They plotted the difference in heat from the surrounding air and that released in the process of condensation and came up with this:

The plot shows that the temperature rise due to latent heating increases dramatically with relative humidity. Moreover, the increase is much larger at 35 °C than at 25 °C, because of the approximately exponential dependence of the water-vapor content of saturated air on temperature. At 35 °C and a relative humidity greater than 60%, the temperature rise due to latent heating exceeds that due to heat transfer from dry air: Latent heating is the dominant factor warming your cold beer.

(Incidentally, this explains why thunderstorms are so rare in the winter: the cold, dense air in wintertime can't hold enough water vapor to store enough heat for them.)

So we've established that beer gets warmed by the release of stored energy as water condenses on the can. What does this have to do with thunderstorms?

Well, consider a cylinder of air that is a mile wide instead of the size of a beer can. Since a beer can is only about 2 1/2 inches wide, this parcel of air is going to be 25,000 times larger, and yet a mile-wide blob of air is not all that big in atmospheric terms. Think of how much stored energy is in that, yet while it's still locked up in water vapor, it's invisible!

Now let's give that cylinder of air a nudge upwards. This nudge could come from encountering a mountain range, or (quite commonly) a lift from a cold front sliding in underneath it and bullying it upward. Once it starts to rise, some of the water vapor will condense as the air cools adiabatically, and a cloud will begin to form. If there is not much moisture (i.e., water vapor) in the air, the cloud might be a small puff or a little layer.

However, given enough moisture (like on humid days), the energy that was stored in that water will be enough to heat that little blob and make it rise even more. As it rises, air from below it will be drawn up to replace it (otherwise there would be a vacuum behind it). The air from below will come up, deposit its moisture as a cloud, and heat itself up. That will make that blob rise, draw up more moist air from below it, and on and on until a towering cumulus (more formally known as cumulus congestus, but you'll usually hear pilots refer to them as "towering cumulus") forms.

This process is what convection is all about, and why pilots are always on the lookout for convective activity. If the atmospheric conditions are unstable enough, that towering cumulus can form into a full cumulonimbus: the dreaded thunderstorm. You can see a dramatic picture of the difference between the two in "Why there is no reason to fly through a thunderstorm in peacetime".


The author is an airline pilot, flight instructor, and adjunct college professor teaching aviation ground schools. He holds an ATP certificate with a DHC-8 type rating, as well as CFI, CFII, MEI, AGI, and IGI certificates, and is a FAASafety Team representative and Master-level participant in the FAA's WINGS program. He is on Facebook as Larry the Flying Guy, has a Larry the Flying Guy YouTube channel, and is on Twitter as @Lairspeed.

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SPECIAL PROGRAMMING NOTE!

You've probably noticed that the last several months of posts haven't appeared. Is Keyboard & Rudder dead?

Not at all. I've just been extremely busy.

What could possibly keep me so busy I haven't written?

Going to the big new world of the airlines, that's what.

Yes, after several years as a happy flight instructor, a recent change in circumstances has led me to enter the Part 121 scene. It's an exciting new world, with new procedures, new routes, and new equipment to learn (for me, the Dash 8), and that's what I've been up to since early this summer.

Once a flight instructor, always a flight instructor, so I'll be writing about the experience of joining a regional airline. Over the weeks to come, I'll be posting a blow-by-blow account of what the process and training is like.

The first posts in the series are about getting ready for the interview, what it was like, and what I've been doing since getting hired and waiting for class to start. If you're considering a career in the airlines, or just wonder what it's like for the "other half", you should find this upcoming series interesting.

Even if you're not interested in going to an airline, I've always tried to glean the best aspects of all types of flying (military, commercial, and general aviation) to make myself and my students better aviators, so you'll probably find something to make your own flying (or learning to fly) a little better and safer.

I hope you enjoy an exciting bundle of posts, and thanks for reading!

The author is an airline pilot, flight instructor, and adjunct college professor teaching aviation ground schools. He holds an ATP certificate with a DHC-8 type rating, as well as CFI, CFII, MEI, AGI, and IGI certificates, and is a FAASafety Team representative and Master-level participant in the FAA's WINGS program. He is on Facebook as Larry the Flying Guy, has a Larry the Flying Guy YouTube channel, and is on Twitter as @Lairspeed.

It takes hours of work to bring each Keyboard & Rudder post to you. If you've found it useful, please consider making an easy one-time or recurring donation via PayPal in any amount you choose.

The "Fun Curve" of Flying

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One of the ways learning to fly changes your life is that it presents you with challenges that you can either face up to or run away from. Dealing with these teaches you about who you are and makes you better at dealing with life's obstacles.

One of these challenges is dealing with learning how to press on even when things aren't as fun. Life itself is a series of ups and downs with its good times and its bad times, and flying is just life on a smaller scale.

Unlike life, however, I have a map for you that will tell you when the good times will be and when the not-so-good times will come. I call it the "Fun Curve":

Click image to embiggen.

It is divided into five stages, with an angry red box in the middle where pilots are made and sorted out from regular people. These stages are:

1. New maneuvers: Everything is brand new and it is amazing. You have no idea what you're doing, but who cares? Just being in the air is as fun as can be, and there's plenty of time to get good at all this stuff later!

2. Pre-solo: There's the first sharp dip in the Fun Curve. You're testing out 50 different ways not to land an airplane, and halfway through you start to wonder if you'll ever get it right. That's when you enter the red box. Those with persistence will be rewarded with even less fun, as flying around in circles around the pattern time after time after time gets wearisome. Just as it gets so close to the bottom as to try even a saint's patience, you get that first solo and things are way more fun again! Those without persistence drop out before that unforgettable day.

3. Post-solo / Cross-country: You've shown you can fly all by yourself, and now you can go out into the practice area and practice what you want, when you want, for as long as you want, without some constant chattering in your ear coming from the right seat. After that, cross country flights take a lot of planning, but they're fun because you're going places you've never been. That's great until it's time for...

4. Checkride preparation: The second sharp dip in the Fun Curve, and the second most common place where non-pilots fall by the wayside. You've spent all that time practicing on your own, thinking you were doing pretty well, and now the right seat is filled with an irritating yipping instructor again. You do the same things over and over again—again. When you're not flying, you're studying for the oral portion. When you're not studying for the oral, you're wondering if you'll pass the flight portion. If you stick with it, eventually you end up getting that second big instructor signoff: the practical test endorsement. You pass and end up as a...

5. Licensed pilot: This is where the one line splits into two.

The green line represents those who continue to learn and master the art of flying. With most things in life, the better you are at something, the more you enjoy it. The more you enjoy it, the better you get at it, so this line goes slowly but steadily upward.

The red line represents those who (in what is an unfortunately common trajectory) stop improving their skills after they pass. Eventually they've seen all their buddies' houses from the air and eaten all the $100 hamburgers they wanted. After that, flying gets dull for them, and they often stop flying altogether.

For the second group, there are two pieces of good news. First, it's often possible to become one of the green liners by deciding to pursue an instrument rating or a tailwheel endorsement or a seaplane rating or doing any of dozens of things that bring the spark of newness back into flying. Second, even if you do drop out for years, after you have your license it's good forever. All you have to do is get with an instructor, brush off the rust, and get back in the air.


The two main things to take from this curve are:

First, if you're at a point in your training that you're starting to doubt whether you'll ever make it (or perhaps you've already dropped out because you thought you where the only one to ever have trouble learning to land an airplane), you can see that you're going through the same thing the other 600,000+ pilots in the United States went through, too. If they could make it, then so can you.

Second, you can see that the curve shoots up sharply after the low points. That's my way of saying, "It may suck right now, but once you get through it, it's fun again. Trust me."

Just like anything involving human behavior and psychology, this curve will not be identical for everyone. However, I've seen this pattern so many times in so many students that it probably won't be too far off for you. If you'd like to share your own experience, leave a comment below.

The author is an airline pilot, flight instructor, and adjunct college professor teaching aviation ground schools. He holds an ATP certificate with a DHC-8 type rating, as well as CFI, CFII, MEI, AGI, and IGI certificates, and is a FAASafety Team representative and Master-level participant in the FAA's WINGS program. He is on Facebook as Larry the Flying Guy, has a Larry the Flying Guy YouTube channel, and is on Twitter as @Lairspeed.

It takes hours of work to bring each Keyboard & Rudder post to you. If you've found it useful, please consider making an easy one-time or recurring donation via PayPal in any amount you choose.

Bringing you what brings the weather

I recently had a chance to visit the National Weather Service office in Cleveland as part of a Northeast Ohio Chapter of the American Meteorological Society event. While the weather happens up above, the people at the NWS are the ones who bring it to you.

Whether you're planning a flight or a picnic, or want to know if you need to go shopping for a new pair of ruby slippers, the forecast you need comes from a two-story building on the west side of the field at Cleveland-Hopkins. The Doppler radar you're used to watching on the TV or on the Internet is right in the parking lot:

The CLE Doppler site. Note the NASA hangar in the background.

This system is what controls it:

Did you ever wonder how that annoying screechy tone and bad weather news gets to your television? Through these stations, that's how:

In the event of severe weather, the staff goes over to one of these units, pushes some buttons indicating what kind and where, and it's on the air.

Close-up of the rack above the monitors. (Click image to embiggen if you want to read the labels.) Still looking for the button that says "Global Thermonuclear War" on it.

I don't think any of these six monitors let you zoom in to see if your long-lost wife is working in the garden, but they do let the forecasters see a bunch of weather data at once:

If that looks like the WKYC Doppler 3 radar image at the upper left, that's because it is. Apparently the radar goes from the dome in the parking lot to Channel 3's office downtown, then gets piped back to the NWS office where it came from in the first place.

One of the more interesting things to happen while I was there took place at this desk:

The windows have a nice view of the airport.

There was a staffer in the chair and I was talking to another one while standing behind it. I mentioned that I keep the TAF site for Cleveland and Mansfield bookmarked on my phone so I can check it easily throughout the day. I asked if this is where they come from and he said, "Sure. Kirk here just put the last one out a few minutes ago."

So I got to meet the guy who writes the crazy TAFs I've written about, and he even spent a while showing me how they get made. I always wondered if they have a mini-model or some sort of local forecasting aid that does most of the work like the continent-wide models do. As it turns out, when it comes to TAFs, it's still plain old looking at the maps and using the brain to figure out what's going to happen—much like a pilot's typical preflight weather planning, but with professional tools. (One of the tools he introduced me to is Bufkit, which is great if you like Skew-T diagrams.)

Many of the places you use as a pilot or as a taxpayer are available to check out. Go see what else is out there for you to explore!

The author is an airline pilot, flight instructor, and adjunct college professor teaching aviation ground schools. He holds an ATP certificate with a DHC-8 type rating, as well as CFI, CFII, MEI, AGI, and IGI certificates, and is a FAASafety Team representative and Master-level participant in the FAA's WINGS program. He is on Facebook as Larry the Flying Guy, has a Larry the Flying Guy YouTube channel, and is on Twitter as @Lairspeed.

It takes hours of work to bring each Keyboard & Rudder post to you. If you've found it useful, please consider making an easy one-time or recurring donation via PayPal in any amount you choose.