A Day Without Cars. Bogota beats the rat race.

Bogota's population grew crazy fast and with it the cars, motorcycles and buses that move everyday.
Q: How fast is 'crazy fast'?

Typical view from my car.

A: 26% from 2010 to 2016. An increase of 2.1 million people.
And that's just the official population (~10M).  The real population is about 14 million.

The cars at rush hour downtown are insane.  They take turns using the roads...even and odd numbered days.  (We don't live downtown.)  Pretty much a similar story as many world cities.

But Bogota takes surprising and novel steps to change.

The coolest one is "The Day Without Cars."  Once a year, private autos and motorcycles are banned from the entire city.  Very simple.

This I gotta see. So, I drove into town.  No! Just kidding!

I tossed my bike in my car, drove to the outskirts of the city and off I went looking for tranquility.

First I headed for the famed intersection of 100th St and 15th Avenue.  Luke and I have been here before and at times have spent more than an hour in the total gridlock that extends for many blocks around this famed hell hole.

But here's what I saw. Nada. Empty.

It wasn't unique.

I was in a Twilight Zone episode...The post-Apocalypse just before the zombies come out.

Taxis were still allowed out.

 I'm totally chilled riding on the street.

Bogota is noted for trying creative solutions.  It's a great story and I encourage you to read of their success.  Bogota had (and still does have) big problems, but they are wrestling with them.

One mayor hired clowns and mimes to direct traffic in an effort to get every one to chill out.

Another mayor painted the crosswalks.

  

But today, The Day Without Cars, was dedicated to learning that we can live without them.

I rode along Bogota's famed ciclovias...Roadways dedicated to bikes and pedestrians.  Bogota's got more of them than anywhere else. And on Sundays, main arteries are closed to cars...Bike's only.

The ciclistas were well-mannered.  They all stopped for traffic lights, even when no cross traffic was there.  Incredible. Many other cities around the globe are following Bogota's example.  Each day Rolos (the people of Bogota) make as many bicycle trips as they do car rides (700, 000 trips per day).

Below are examples of the dedicated bike paths.  Birthing this bike-friendly city must have been hard (See the history here).  And judging from the other 364 days of the year, the birthing is still going on.  But today was great.

I won't forget the ride home on the dreaded Autopiste Norte. Nothing happened. How sweet.  

I can't wait until next year.

I saved the map of the bike-only streets.  Next time, I'll go end to end.

The Chernobyl of Chingaza.

Whoa!  All Stop!
As Luke and I reached the bottom of the Chingaza mountains, we saw a deserted wasteland.  A massive abandoned factory tucked into a corner of a valley.

It was straight from a creepy horror film, so we followed the script and we 'snuck up' on its massive bulk.

 Beyond it, we saw a mountain cut away and now abandoned.

We had stumbled upon the Samper concrete factory, the first and formerly largest concrete factory in Colombia.  Abandoned now for about 20 years, the factory and adjacent small town are now ghosts.

There's a big story here.  And others have told it better than I.  Here's a link to start.
Luke discovered that the factory's shut down was related to its potential for pollution of the adjacent water sources for Bogota.
The factory was started about 1909, in large part to support the construction of the area's first hydroelectric dam.  (Here's a link to that part of the story.  See page 281.)

I noted that the Mexican cement conglomerate CEMEX bought Samper at about the same time as the factory was shut down.

Nor were Luke and I the first to photograph.  Here's a National Geographic take (follow link).
But I think Luke's photos are better.  It'd be moving to go back when the light is just perfect to tell a scary story (with permission, of course).  ;-)

God's Night Mountains...Chingaza.

No one lives on God's Night Mountains, Chingaza.

No one spends the night.
But our friends, German and Fernando, got permission to hike to some of the sacred lakes, Laguas de Buitrago. (Map here.)

In lakes like these, the ancient Muisca and Guayupe peoples made their offerings of gold that gave rise to the legends of El Dorado, the City of Gold.  And that of course led to the subsequent Spanish plunder of Latin America.  (Lesson here: If you got it, don't flaunt it.)
This photo is a golden raft from Bogota's Gold Museum.  The raft (about eight inches long) was an offering made long ago (1000 years give or take) and recovered in 1969. 

Today, much more precious than the golden raft is the pure water supply for the 14,000,000 people of Bogota.  And the purity of Bogota's water is why access to Chingaza is so difficult to get.  Fernando and German, worked far in advance to set up the trip.   (Thanks, Guys! They are both US Naval Academy grads and classmates of mine.  Definitely the guys you want on your team.)

Our brains rattled as we drove up the impossibly long, rutted and steep dirt roads to about 11,500 feet altitude.  But we were tough, and we were only mildly irritated by the hundreds of cyclists that were making the 40 kilometer ride up the same roads.  OMG!  These weekend Bogota ciclistas make the Tour de France look like a coast along the Ocean City boardwalk.  The thin air of Bogota can make life tough for us flatlanders.  But these Colombian guys and gals race up mountains three miles above the ocean! On bone-rattling dirt roads!
Can you hear me down there along the coast? Or is the air too thin up here for my voice to carry?
[To be clear, I was in a Toyota SUV with a full tank of gas and air conditioning; I was not on a bike.]

German and Mrs.

Let me catch my breath...  Okay, back to work.

Much of the Chingaza is above the tree line, but the dense, low vegetation traps the fogs and clouds to keep everything green in this unique alpine tundra ecosystem, called the Paramo.  Check out Wikipedia for the details and here for excellent photos.

Our group just marveled at the beauty and shared the happiness.

Luke at 11,800 ft.

Fernando's family

Laguna de Buitrago

"Rabbit ears" grow only 1 cm per year.  Many are 2 meters tall.

All so very pretty and peaceful...
Until we stumbled upon The Chernobyl of Chingaza.

Schoolyard Science #5: Coriolis, Down the Drain

During our visit to Quito Ecuador, we spent an afternoon visiting the equator and its adventures in physics.  See how the  water goes down the drain differently (circularly), even though the three basins are only about six feet apart.

North Hemisphere (above).

Southern Hemisphere (above)

On the equator (below)

This proves the Coriolis effect that you've heard before.  Right?

Are you now a true believer?

Don't be.

Apparently it's a trick.

The Coriolis forces can only kick in over long distances.  Think hurricane.

The good folks at National Geographic tell us "Despite the popular urban legend, you cannot observe the Coriolis effect by watching a toilet flush or a swimming pool drain. The movement of fluids in these basins is dependent on manufacturer’s design (toilet) or outside forces such as a strong breeze or movement of swimmers (pool)."  (Or in our video cases shown above, the water for the north and south examples wasn't perfectly still, as it was in the "test" performed directly on the line.)

Oh well.  Don't you just hate a spoiler?  Anyway, We enjoyed watching the sink drain. ;-)

For a full explanation, see Wikipedia here.  And here's a summary:

"As the Earth turns around its axis, everything attached to it, including the atmosphere, turns with it (imperceptibly to our senses). An object that is moving without being dragged along with the surface rotation or atmosphere such as an object in ballistic flight or an independent air mass within the atmosphere, travels in a straight motion over the turning Earth. From our rotating perspective on the planet, the direction of motion of an object in ballistic flight changes as it moves, bending in the opposite direction to our actual motion. When viewed from a stationary point in space directly above the north pole, any land feature in the Northern Hemisphere turns anticlockwise—and, fixing our gaze on that location, any other location in that hemisphere rotates around it the same way. The traced ground path of a freely moving body in ballistic flight traveling from one point to another therefore bends the opposite way, clockwise, which is conventionally labeled as "right," where it will be if the direction of motion is considered "ahead," and "down" is defined naturally."

Here's more from the Wikipedia killjoys:

"Contrary to popular misconception, water rotation in home bathrooms under normal circumstances is not related to the Coriolis effect or to the rotation of the Earth, and no consistent difference in rotation direction between toilet drainage in the Northern and Southern Hemispheres can be observed.[49][50][51][52] The formation of a vortex over the plug hole may be explained by the conservation of angular momentum: The radius of rotation decreases as water approaches the plug hole, so the rate of rotation increases, for the same reason that an ice skater's rate of spin increases as they pull their arms in. Any rotation around the plug hole that is initially present accelerates as water moves inward."

Life was more fun in the days of a flat earth. ;-(

Schooyard Science #4: Getting into hot water.

More on living at Bogota's very high altitude (8,300 feet above sea level)

Next demonstration.
We ran a little experiment and boiled water.  (We did not watch it boil.)
The theory says that the lower atmospheric pressure will allow water to boil at a lower temperature (less atmospheric pressure making it easier for low energy molecules to escape the pot...another way to say "boiling";  lower temperature=less molecular kinetic energy)

Here's the result.
The water boiled at 199 F; not the 212 F that we observe at sea level.

Checking our handy copy of the steam-water equilibrium graph (Which I've been waiting to use since my last thermodynamics class in college! See diagram to the right.), we see that a temperature of 199F has its boiling pressure at about 11.45 psi, which turns out to be about 77% of the pressure at sea level.

And we remember from an earlier posting that the predicted air pressure in Bogota's altitude is 11.5 psi, 77% of the air pressure at sea level.

Hurrah! Thermodynamics is safe for another day! (Whew!)

That's it for today, kids!
You can try this at home.

#4
(On a personal note, only after about two months living at 8,600 ft. did I finally reach a point of sleeping through the night without waking up at least once feeling out of breath.  In general we don't huff and puff as we used to.  So, we've gotten used to the thin air.)

Schoolyard Science #3. Take Off!

  

Okay class, We're revisiting  altitude and atmosphere...

Quick review:
Bogota is one of the highest cities in the world  (Denver's at 5,300 ft.  Bogota's at 8,300 ft / 2,500 meters.) Check out the graph from Wikipedia...
Bogota has about 77% of the air that Miami has.

[Special Shout Out to Buck Buchanan, ace instructor at Airbus.  Thanks, Buck!
Any errors in this blogpost are mine. Buck did not check my final posting.]

We've been on a couple of airplane flights between Bogota and cities along the coast, and we made some interesting observations.
First a little background music...
When a jet plane accelerates to take off, it grabs air from in front of the engines, and shoves it out the exhaust at very high speeds.  (There's other stuff going on too, but that's the big idea.)  The accelerated air causes the plane to move forward. (No.  The exhausting air doesn't "push" on the static outside air.  See me after class if you have questions about this.)
The plane builds up speed, and when it reaches 150 knots, the pilot tips the plane up and the plane takes off.  The pilots call this speed "VR".  At sea level, this acceleration takes about 30 seconds to get from zero speed to 150 knots (VR).  Here a sketch from Wikipedia.

So what's this got to do with Bogota?

Here's a photo of a timer I used to record how long it took to get airborne from an airport near sea level.

That's cool. About 33 seconds to take off at sea level. 

Yawn.

Ok Class. But what happens if the air is less dense, say if you landed in Bogota and your now going to take off?
- Does it take longer to accelerate to 150 knots? Less time?
- Do you accelerate faster because there's less wind resistance (the air is thinner.)?
- Do you need a longer runway or a shorter runway?  (Said another way...Will you run into the nursery school that's at the end of the runway? Ugh...)
- Is 150 knots the speed you need? More or less?

Here's the answer, from a recent take off from Bogota's airport.

Whoa!
Taking off in Bogota takes about 40% more time than in Miami! (46sec/33sec = 140%).
It's true, because the planes in Bogota accelerate more slowly than they do in Miami...even when the engines are running at the same speed.  (We checked :-)  Two engine aircraft always set their throttles to the same value for take-off*.  That way the engines are most efficient and operate most cost-effectively.)

But wait.  Does more time needed to take off mean planes require more distance to take off?  After all, they're moving more slowly, right?   The pilots of the plane told me that take off speed was about the same for Miami and Bogota (150 knots). (Yes.  I asked them. And you can check it out here.)

For any former high school physics students, here your challenge question:
Assume that:
1. The take off speed for an airplane is the same at any altitude.
2. And at a higher runway altitude it takes 46 seconds to reach take off speed, and at sea level it takes 30 seconds to reach that speed.
3. Acceleration from break release through take off is constant.

Tell us:
- How long is the takeoff distance in Bogota compared to Miami? Show your work.
Post your answers on this blog. :-)  It's okay to show off.
(Hint: Use a graph of velocity vs. time.)

Bonus question.
Now, Why does the plane accelerate more slowly?  Show your thinking. :-)
Hint: F=ma.
First think about the mass of the air that's going into the engine.
Assume that the air accelerates from zero at the engine intake to some exhaust velocity. (It doesn't matter what the actual velocity is.)
Assume that the engine's rotation speed is the same in both scenarios.  (It is.)
Next make a simplifying assumption about the mass of the fuel that's added to the engine.
Compare this generated force (which is now acting on the mass of the airplane) with the acceleration of the plane in the two altitude scenarios.  Go ahead, you can do it.

Your answer won't come out exactly, because there are other factors that affect the take off time, buot I think you'll be impressed at how close you'll get.  Good luck!

Amazon Creatures Two: Dolphins and Sloths

Spoiler Alert: All those fabulous photos of pink Amazon river dolphins really are fabulous and their photographs should be praised and honored for their patience (or luck).  If you want to see those photos, follow the link.

However, this is real life and your humble reporter didn't have the (time) resources to wait a month or two, or three, to wait for the pink river dolphins to jump up.  We did scour the river looking for them, and did find a few.  However, their habit is to stay underwater.  (Go figure.) And unlike their grey dolphin cousins, their dorsal fins in quite small, so when they pop to the surface, an observer (and camera) have precious little time to respond.

We did our best to get a photo to share with you.  They typically hang around at the mouths of larger tributaries to the Amazon.  We spent our time at the mouths of the Narina and Amacayacu rivers.  (See map.)

In this photo, you can see a mother and calf  surfacing briefly.  You'll notice the absence of pronounced dorsal fin.

This photo shows a hint of the pink color for which they are noted.

This view was typical when they'd surface for a breath.  Pink river dolphins are about 6 feet long.

The grey river dolphins were easier to spot, but they are tiny...about 2-3 feet long at maturity.

Here she comes...

There she goes... 

Teasing us with a peak. But nothing more.

A pair keeps their distance.

They were fun to watch, but you'll have to go there in person to enjoy fully.  Let me know when you want to go, and we'll have a great trip.

My idea of a sloth

Sometimes the hardest animals to find are those that move the slowest.  Always up for a challenge, we went looking for a sloth.  Those cute and cuddly critters that hang from trees and smile. (See right.  Photo credit here.)


First we crossed the Amazon and made an undocumented (i.e., extralegal) stop in Peru, where we had heard there was a sloth family hanging out near a small yuca farm. (Hanging out.  Yuca Yuca.  Get it??? Yuca Yuca?)


We craned our necks, stared into branches, circled and sniffed. Nada. Zilch.

Back to Colombia and try again another day.

Next day, this time in Colombia, we search again.

Hurray! Near our farthest most search (way out to the west on the map), our guide Reinaldo spots a sloth high in a tree.
We stared and stared trying to see what he saw. (We were in a boat, and re-positioned it several times.)
Eventually we saw it.  Actually, we saw an unkempt hairball that had got stuck on a branch.  This is it.

Confused?  Where's that cute baby sloth of our dreams?

Would you like some orientation about what you're looking at?

This sloth is laying on his back on a branch, and you're looking at the less-than-photogenic end of his torso (not his head).

His right lower leg is sticking up to the left.  His left arm is reaching up towards the right.  The other hairy parts?  I'm not quite sure.  

His head is on the far side of his body, out of sight.  He peeked out once in the 20 minutes we watched him. (no photo :-(  )

Did you know that sloths seldom move?  It's true.

Here's the action photos we got.

Amazing, uh?

If you want to go on a sloth photo hunt adventure, ummmm, let me know when to expect you back.

I've crossed sloths off my list. :-)

Cheers!