to READ THE FIRST FEW PAGES

BIRDBRAIN PUBLISHING LLC F o r U p To D a t e I n f o r m a t i o n a n d E x t r a M a t e r i a l , G o To w w w. b a s e - b o o k . c o m

Contents

BirdBrain Publishing Planet EARTH www.base-book.com Copyright 2010 by BirdBrain Publishing All rights reserved. No part of this book may be reproduced in any form, or by any electronic mechanical or other means, without the permission in writing from the publisher. Written by Matt Gerdes Edited by Mary Catherine O’Connor Layout by Matt Gerdes & Loren Cox All Graphics and Illustrations by Loren Cox Cover Photo: Dean Potter meditating on ‘The Ecstasy Board,’ the largest BASE jump in the world at the time of printing, and an exit he opened in August of 2009, together with Andy West. Photo by Corey Rich Inside Cover Page: Mattt G above the Gorges du Verdon, France. Photo by Dom Daher. Gerdes, Matt The Great Book of BASE: BirdBrain ISBN 9780984555611

Disclaimer................................................6 Forward....................................................8 Introduction..........................................12 1 Before You Begin...............................16 2 Begin With the End in Mind............22 3 Pre-BASE Training.............................26 4 Objects................................................40 KL Tower................................................56 Castelton Tower.....................................58 5 BASE Gear...........................................62 Bridge Day..............................................76 Lauterbrunnen.......................................78 6 Deployment Process...........................82 7 Choosing Partners..............................88 8 Ethics...................................................94 9 Packing to PLF..................................102 10 Jumping Progression......................116 Moab.....................................................136 Norway..................................................141 11 Weather............................................144 12 History.............................................164 13 Technical Info..................................178 A Short Career......................................189 A Line for the People...........................192 14 The Whole Earth.............................195 15 Sub-section, Static Lining...............200 16 Whole Earth (Continued)..............205 17 Advanced Tech. (wingsuit).............216 18 Tracking & More.............................228 19 Staying Alive....................................244 Appendix...............................................253 Thanks...................................................266 Index......................................................267

Photo by Ricardo Valbuena. Edited by Jhonathan Florez

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T H E G R E AT B O O K O F B A S E

Warning!

No reason to sue, it’s your fault

Warning!

No reason to sue, it’s your fault

The Great Book of BASE is NOT an instruction manual. You cannot learn to BASE jump by reading this book. The content here is offered for entertainment purposes ONLY.

THE INFORMATION HEREIN IS PRESENTED “AS IS” WITH NO EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO ANY INFORMATION PROVIDED and THE AUTHOR AND PUBLISHER SHALL NOT BE LIABLE FOR ANY INJURY, COST, OR DAMAGE ARISING EITHER DIRECTLY OR INDIRECTLY FROM YOUR ACTIONS. IT IS SOLELY YOUR RESPONSIBILITY TO EVALUATE THE ACCURACY, COMPLETENESS AND USEFULNESS OF ALL OPINIONS PROVIDED HERE.

YOU and ONLY YOU are responsible for your actions and for your life. By reading this book, or even opening or barely touching it, you agree to take FULL RESPONSIBILITY for your actions in life.

IN NO EVENT WILL THE AUTHOR OR PUBLISHER BE LIABLE FOR ANY INCIDENTAL, CONSEQUENTIAL, OR INDIRECT DAMAGES TO YOU OR ANY PROPERTY.

If you BASE jump, or even attempt anything like BASE jumping, YOU COULD DIE. This book discusses an activity THAT CAN KILL YOU.

By reading this book, you agree to indemnify, defend and hold harmless the author and publisher and all related employees, agents, and suppliers against all losses, expenses, damages and costs, including reasonable attorneys’ fees, resulting from any violation of this Agreement (including negligent or wrongful conduct) by you or any other person who reads this book.

READ THIS!!! WARNING: this book discusses a dangerous and lethal activity! BASE jumping is extremely dangerous. It is so dangerous that we seriously encourage you to not do it. In fact, we honestly think it’s a bad idea.

NO WARRANTY IS OFFERED AS TO THE COMPLETENESS OR ACCURACY OF THE MATERIAL IN THIS BOOK. BY READING THIS BOOK, YOU AGREE TO BE BOUND BY THE TERMS AND CONDITIONS SET FORTH BELOW. IF YOU DO NOT WISH TO BE AND AGREE TO BE BOUND BY THESE TERMS AND CONDITIONS, YOU MAY NOT READ THIS BOOK. This book is the sole opinion of the author. The information herein is not intended as advice and should not be used to replace any training. This book was written merely to entertain the reader. If you do anything recommended and/or suggested in this book, you do so at your own risk. The information in this book cannot replace proper training!!!

This book is solely intended to be the author’s opinion for reader entertainment and is not professional advice. The information provided is intended to entertain readers only. The author, publisher, and any employees, agents, suppliers, and any third party information providers expressly disclaim any responsibility for any damages, injury, or fatality occurring as a result of use of the opinions included in this book. By reading the information contained in this book, you agree that you understand that the content provided is for entertainment purposes only.

Neither the publisher nor the author shall be liable for injuries, deaths, or damages arising from your participation in the sport of BASE jumping or anything related to the sport of BASE jumping.

There may be errors in this book resulting from the mistake of the author and/or the people with whom he consulted. The information was gathered from a variety of sources, which may not have been independently verified. Those who provided the information may have made mistakes. The author may have made mistakes in the conveyance of the information in this book. The author cannot, therefore, guarantee the correctness of any of the information contained in this book. You must keep in mind that the information in this book may be erroneous, so use your own best judgment.

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T H E G R E AT B O O K O F B A S E

The author, editors, and publishers advise readers to take full responsibility for their safety and know their own limits. The publisher and the author make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, without limitation.

FORWARD

FORWARD

Forward By Harry Parker The book you are holding in your hands represents the most comprehensive look at BASE jumping to date. BASE jumping is an underground sport and is highly susceptible to passionate, highly varying interpretation by the jumping community. Finding common ground is rare and everyone has an opinion. With the recent decade of explosive growth in this otherwise nonmainstream sport, this book is long overdue. Back in the 90s, it was hard to get anyone to agree. The Cliff Jumpers Association of America (CJAA), founded by Dennis McGlynn, represented the second generation of jumpers attempting to find some common ground in practice, theory and thought. The heart of the effort was to forge unity in hopes of getting access to sites, especially to our National Park System, without having to run from the cops. In 1997, the CJAA published “The CJAA Guidelines” providing the first real look at acceptable BASE standards and practices, through the eyes of the most highly respected manufacturers of the time. This publication was written for our survival. During that time, real unity occurred. Legal events began to emerge, concentrating on competition through the International Pro BASE Circuit (IPBC). Through these events, a generation of BASE jumpers was trained in packing, exit, and landing technique. The events opened up many sites which are taken for granted today. Mentors became full-fledged instructors with evolving courses, manufacturers took a quantum leap in their business practices, and equipment reached safety levels never before thought possible. More than ten years ago I tried to visualize what the sport would be like as jumpers would come from other disciplines, such as climbing and hang gliding, and from the other outdoor sport communities. In order for access to actually happen, our activity needed to cross the cultural lines of sport. And it has. During my time fighting for access I saw an obvious culture inevitability: We were backcountry parachutists learning to navigate a world that was completely foreign to the DZ we came from. We were placing ourselves in the open and possibly dangerous wilderness. It was dangerous because we were not trained, and we were the foreigners. Hiking six hours into the backcountry can get you in a lot of trouble and change your life forever if someone breaks a femur and you don’t know what to do. Weather changes in an instant and can make an exit next to impossible. When you add BASE jumping variables to backcountry risks, you create a potent statistic cocktail. Matt Gerdes is a professional paraglider pilot who has been involved with the paraglider testing and design industry for a decade. He has racked up more than 2,000 hours of flight time at sites all around the globe, with a perfect safety record. Matt has made over 550 BASE jumps (at the time of printing), and his experience as a paragliding instructor for more than 10 years gives him the perspective needed to compile a book of information such as this. Matt’s complete immersion in outdoor sports also includes big wall climbing and backcountry skiing with many years of experiences, both good and bad, in the open wilderness. His combination of mountain sports and the years spent doing them has created an excellent lens through which to view our sport of BASE jumping. Just reading the weather portion of this book is worth the cover price. As many BASE jumpers leave the states and flock to the big mountains of Europe and beyond, many of us go unequipped to meet our real nemesis, the land and earth itself. Just ask anyone who has spent an evening, unprepared, on the top of a Norwegian wall.

Nothing is perfect, and no book can encompass every detail of any one subject, nor every viewpoint. Every book is subject to the eyes that wrote it. What you are holding in your hands is one of only a few published works on the guts of BASE. It includes theory and discusses standards of acceptable practice for the sport you love. Many have given their lives to learn some of these valuable lessons and much of the info in this book is probably already out there somewhere. What makes this book invaluable is the comprehensive nature of the information and having it all in one reference -- written specifically for BASE jumpers by a BASE jumper. As BASE jumping moves into the next decade and our sport opens more possibilities for practice, some hope that we, as a group, further cross-train and educate ourselves. Being safe, respectable and professional isn’t just about being able to exit stable anymore. After sampling this book I can’t help but wonder what the next ten years will bring to the sport of BASE jumping. What I do know is that the sport is always in need of comprehensive and accessible information, like this book. People like Matt should be supported in their efforts to bring out the best in ourselves and our sport. I’ve stood on the edge with Matt a couple of times. He is focused, motivated and an experienced jumper; but above all, he is humble. Buy this book; read it, practice it, share it.

-H.P.

Harry Parker’s skydiving career spans more than 20 years and his BASE jumping career almost as long. While attending the University of Florida, Harry was president of the University of Florida Falling Gators, and took the team to its first Collegiate competition in 1989. He also created a demo team that served the surrounding area. After college, Harry traveled the US as a rigger and videographer for skydiving events, concentrating on the boogie circuit, which brought him to live in California after more than five complete cross country trips. During that time Harry grew into BASE jumping and was fortunate to experience some of the most pristine natural jumping sites that the US has to offer. In 1994, Harry became one of the founders and president of the Cliff Jumpers Association of America. The CJAA organization was dedicated to unifying, standardizing and creating access for BASE jumpers in the United States. This organization and its members created some of the first real organized, open and legal BASE jumping events since the inception of Bridge Day. Shortly afterward, he partnered with Dennis McGlynn and Avery Badenhop and the three formed the International Pro BASE Circuit. The IPBC was dedicated to many facets of BASE jumping: raising experience and proficiency levels, standardizing equipment and theory, and increasing site knowledge and site access through competitive BASE jumping in the US. Above all, the IPBC was committed to pushing the edge in all directions of what could and, as others sometimes said, couldn’t be done. By the time the late 90s rolled around, the IPBC was running Bridge Day and holding international BASE demonstration events throughout Asia, attracting hundreds of BASE jumpers, both new and seasoned. Throughout the years, Harry has concentrated more and more on his skydiving photography and video. You can still find Harry at Bridge Day, announcing all the thrills, chills and spills of the event. Harry Wingsuiting Kjerag, 2003 www.TheHarryParker.com Photo by David Major

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THE DEPLOYMENT PROCESS

CHAPTER 6

The Deployment Process Links in a Chain Understanding the chain or sequences that lead to a successful canopy deployment is important and relatively simple. There are many malfunctions possible in the sequence, any one of which can kill you if allowed to happen. From your pilot chute to your leg straps, your equipment forms a chain in which every link is vital to your survival. Treat your equipment, the sport, and your progression as if your life depends on the perfect deployment of your parachute and the flawless piloting of your canopy. The Pilot Chute

It goes without saying that although you must deploy your pilot chute (PC) in a clean and balanced manner, you must also throw it as though your life depends on it, because it does. A weak pilot chute toss can lead to a pilot chute hesitation, in which the PC struggles to inflate in the turbulence behind the jumper (the burble). It can also encourage bridle-PC or bridle-jumper entanglements, particularly if during an unstable or aerobatic deployment. Once you deploy your pilot chute into clean air and it inflates fully, extends your bridle, and begins to open your container, the deployment process has begun. Photo and sequence by Bryan Rapoza

Find Balance... Don’t overthrow! Certainly, throw your PC as if your life depends on it, but overthrowing may cause your PC to oscillate, rotate, and lead to asymmetric canopy extractions and off heading openings. Not to mention the fact that it will probably ruin your body position.

also increase the amount of time that the packjob has to rotate before beginning line stretch. Most off-headings are already decided before line stretch occurs, by a rotation of the packjob. Packjob rotation can be caused by countless variables: • The packjob is influenced by the container walls due to bad body position.

Bridle Extension to Packjob Extraction

• An asymmetric or imbalanced packjob tilts or turns because one side is heavier or more influenced by airflow.

BASE bridles should be at least nine feet in length from the pin or shrivel flap to PC. This should allow the PC to extend beyond the worst of the jumper’s burble into clean air, and also provides a long enough lag time for the PC to generate ‘snatch’ force with which to extract the packjob from the container.

• The center cell is asymmetrically folded into the packjob, and when pulled by the PC, tilts or rotates the packjob as a result.

The pilot chute alone is responsible for removing the canopy from the container and bringing it to line stretch. Although the canopy itself will begin creating drag and encouraging line stretch on its own once it has cleared the container, the pilot chute will continue to serve its purpose until bottom surface expansion of the canopy has begun.

• Center cell strip caused by a too large PC seriously deforms the packjob, encouraging asymmetric inflation.

This is where we see why pilot chute size is critical. A too large PC will cause excessive center cell strip, which will deform the packjob, perhaps asymmetrically, and thus negatively affect the opening and heading performance. A too small PC will increase the timeline of the deployment process, leading to a critical loss of altitude, and will

• Wind, particularly in the case of low airspeed (short delays) deployments, affects the packjob or causes the PC to pull from one side.

Once the packjob has been extracted from the container it will create drag and aid the PC in line extension. Although the gradually unfolding packjob is creating drag, the PC is still working at this point as well and plays an important role in the deployment process until total line stretch is achieved.

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ETHICS

CHAPTER 8

the leave no trace idea is that we don’t have to make anything any worse than it really needs to be. We don’t need to drive to the store if we can walk in a reasonable amount of time, and we don’t need to cut trees down to get a better movie shot. On a less environmental note, the leave no trace theme is just as important at other objects, where local jumpers will not benefit from the general public being made aware of their actions. If you’re going to access the roof of your friend’s apartment building downtown and jump from it, then the less people who find out about it, the better your chances are that you’ll get to do it again. Leave no trace - no litter, no damage, no stickers. It’s a simple rule.

Don’t Get Caught

There are countless legal objects in the world, enough to keep you busy for the rest of your life without ever jumping the same one twice. So there is no good excuse to get caught and possibly ruin access to an illegal object that other jumpers might be enjoying safely and discretely. Jumping an illegal object and then getting caught is bad for you, bad for the sport, and bad for everyone else in it. Try not to be that guy or girl who ruins it for others – it is a small community and we will not let you forget your carelessness any time soon. And you will deserve the jeering ostracism if you do. The excitement of sneaking around at night is irresistable for many jumpers, so check out the legality section just in case.

Who Is a BASE Jumper? We are young, and we are old. We are professionals, and we are transient wanderers. We are doctors and lawyers and firemen and train conductors. We are tradesmen and intellectuals, philosophers and teenage thrill seekers. We are men, and we are women. Although we can estimate with some precision that the majority of BASE jumpers are single males between the ages of 22 and 40, this sport attracts men and women from all walks of life. I have jumped with a nurse, a race car driver, an airline pilot, and a stuntman, all at the same time from a cliff in the Alps. Our common bond is a strong one, and transgresses all other cultural or social boundaries. It is not uncommon to meet people from four or five different countries at a single exit point, and for long-lasting friendships to form between people from totally different parts of the world.

Don’t Get Injured (or Die)

Accidents suck. They suck for you most of all, they suck for your friends who have to care for you or scrape your body off the ground, and they suck for everyone else in the sport. It would be great if BASE jumping made the news for more positive reasons, but at this point in time the vast majority of media coverage revolves around accidents and illegal acts, which does little other than make us look like danger-craving criminals, which we are not. Do your part to preserve yourself, and our image.

ETHICS

CHAPTER 8

Opening Objects

The whole world is jumpable, almost. Once you have been infected with the BASE mindset, you will never look at high objects the same. Buildings, bridges, cliffs… everywhere you look, possibilities exist. The fact is that quality unjumped objects that require less than a few days walk or a long helicopter flight are extremely rare. This means that, if you are looking at what you think is a fantastic object, then the chances are it has already been jumped before or is still being jumped regularly. Do your research and find the locals who will have the necessary information to help you jump the object safely. If you have somehow stumbled upon a quality potential BASE object and after extensive research, no one seems to know anything about it then it may be your turn to “open” the object. Jhonny and Ren. Photo by Harry Parker. This is something that is generally left to the most experienced jumpers, and the knowledge required to do it safely is far more than could fit within the pages of any book. The basic rule is, again, to leave no trace. No matter the object, BASE jumping should be a zero impact endeavor. We don’t leave mountain bike tire tracks, or climbing bolts and chalk. We don’t need to mark our path or cut any trees. The environment need not suffer for our presence. After opening your object, you are faced with the decision of whether to tell everyone, no one, or just the right people. Consider that the people you tell will certainly tell others, and depending on the quality of the object its popularity will grow accordingly. How much traffic can this object withstand before it becomes a liability to the sport, and to you? Think carefully before spreading the word.

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T H E G R E AT B O O K O F B A S E

PACKING TO PLF

CHAPTER 9

PACKING TO PLF

CHAPTER 9

From Packing To PLF Packing Your single parachute system must open and function correctly on every jump. If it does not, the consequences will almost certainly be undesirable. Thus, packing is a massive part of jumping, but many new jumpers let too much ride on their packjobs and not enough on the other factors surrounding the opening of their parachutes. A canopy that has been meticulously prepared over the course of an hour by a focused jumper who chooses to use it in high winds will not necessarily open better than a 10 minute ‘trash-pack’ jumped with good body position in the right conditions. Plenty of rapid and careless packjobs have opened perfectly, and plenty of perfect packjobs have ended in disaster. Therefore, while clean and careful packing should be considered mandatory, it is also important to understand all of the factors which determine the outcome of your opening. Learn the Details Immerse yourself in packing, and understand the process completely. The more you understand about packing technique, the greater your awareness will be of the relationship between you and your equipment.

The key to packing, perhaps, is to find your balance of speed and meticulousness, and to understand that factors such as weather and body position make up a large part of the links in the chain of a safe parachute opening. Most experienced jumpers use the broad and totally generalized estimation that body position is around 80% of opening performance, with the majority of the remaining 20% reliant on packing and weather factors. However, that is assuming all factors are normal, including weather conditions. If you take your perfect packjob off a cliff with perfect body position in turbulent wind conditions, then the probability of a clean opening is dramatically reduced, and most would agree that a 180 or worse would come as no surprise. Additionally, if one of those quick and careless packjobs opened with a malfunction, even in the possession of a veteran in perfect conditions, no one would be surprised. If packing carelessly or jumping in sub-optimal conditions works 99 out of 100 times, and failure means serious injury or death, are those odds that you want to play? You shouldn’t, if you want to live a long healthy life, and the case for packing carefully and choosing good conditions is clear cut. Don’t allow the process of packing your rig become a tedious chore. If you can’t learn to enjoy it, at least accept it as an essential and unavoidable part of perhaps the most amazing activity that you can ever engage in. Before you start, consider the following points. Focus

Choose an environment that is comfortable and free of distractions: The surface should be clean not hard or slippery. Shag carpet, for instance, is far preferable to hard tile; kneeling on tile or concrete isn’t fun, and your canopy and container will slide

*Assuming reasonably appropriate jumping conditions. Note that totally inappropriate weather may override all other factors. **Assuming appropriate, modern, quality equipment. Note that outdated or poorly maintained or assembled equipment may override all other factors. Also, the Packing slice shown above assumes reasonably clean and correct packing. Note that terrible or incorrect packing will override other factors.

Consistency is Key If you always pack the same, then when something irregular does occur, you can potentially remove the packing variable as a major cause of the result.

around and it will be more difficult to maintain line tension. Manicured green grass is a favorite surface for many jumpers. It is soft, the rig is not prone to slide, and you can often use a stake instead of packing weights. Particularly during your first hundred packjobs, you should try to pack someplace where you won’t be interrupted or distracted from your task. If you find a nice grassy spot near a horde of attractive sunbathers that you can’t keep your eyes off, maybe choose another spot. If ten of your non-jumping friends are admiring your newfound bravery and skill and wondering at the gravity of your project, ask them to not talk to you until you’ve completely finished everything. If they ask you a question and you stop to answer it, and then forget a step, then you won’t be the first person to fold tools into the container, or to forget another important step that could lead to a fatality. Simple, stupid, basic packing errors can kill. Prepare in the Appropriate Environment

Before you begin packing, be sure that you have everything you need close at hand. You shouldn’t have to go and find a pull up cord or a clamp or a tailgate halfway through

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MOAB

Moab: Subterminal Paradise By Steph Davis If you like slickrock, low cliffs and no hassles, you will probably like jumping in Moab. If you also happen to like rock climbing, camping, mountain biking, river rafting, paragliding, speed flying, skydiving, rock hounding, canyoneering, trail running, motocross, skiing and/or drinking beer that’s not too strong, then you’ll probably move here. It’s no exaggeration to call Moab a sub-terminal BASE paradise. Moab, a town of 5,000 locals, is home to around four local BASE jumpers, just as in the early days. But it is now a major destination. A Cessna skydiving operation fills in the gap for those craving terminal altitude and can help relieve the disappointment of being winded out. Many exits can be reached in under an hour, though simple to difficult scrambling can occasionally be required and sometimes even roped technical climbing is necessary. Three to four hundred foot cliffs are the norm, though you can find plenty of 200-footers, if that’s what you’re into. The ease of access, the beauty of the visuals, and the completely hassle-free lifestyle of Moab make the sub-terminal world pretty addictive. It’s hard to say who did the first jumps in Moab. Alf Humphries was most likely the first. From 1991-3, he opened several exits with a small crew. Kevin McGuire did the first jump from the Tombstone, the most wellknown cliff in Moab. In the early 90’s, word spread around to other jumpers when a few BASE videos of Dennis McGlynn started to appear. He was jumping beautiful red cliffs with vague references to location. Almost every other place with steep, accessible cliffs in America seemed to concoct rules against it as soon as jumpers appeared. So the first Moab visitors were torn by the urge to share and the instinct to keep it on the down low. By 1999 there were a handful of known exits, though

Steph at Tombstone. Photos by Diego Calderoni.

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WEATHER TO BASE

CHAPTER 11

WEATHER TO BASE

CHAPTER 11

Mechanical Turbulence

Wind interacting with terrain and objects creates mechanical turbulence. This is a readily understandable situation; much like the currents in a river which eddy and turbulate behind rocks, the leeward side of objects will almost without exception feature turbulent air. Higher wind will create more turbulence, and because high wind is not conducive to safe BASE jumping, mechanical turbulence is not something that you should encounter very often, or ever, if you choose your conditions responsibly. However, a classic example would be an acceptable amount of valley wind in the landing zone several thousand feet below an exit point in light or no wind. Obstacles in the valley such as trees or buildings can create turbulence downwind that, even in winds as light as 10-15mph, can make landing conditions less than ideal. Understanding rotor can save you from injury or worse. The diagrams below and top right show that turbulence extends downwind of an object for increasing distances in higher winds. It should be obvious that landing downwind of uneven terrain, trees, or manmade obstacles is far less preferable to landing in clean air. Although BASE canopies are all relatively resistant to collapse, you can still suddenly lose altitude due to sinking air, or experience large pitch oscillations which will require brake input and reduce airspeed and flare energy needed close to the ground. Use this knowledge to choose your landing zone ahead of time, and plan ahead.

Mechanical turbulence in the mountains. Atmospheric wind is compressed at ridges and peaks, then turbulates in the rotor on the leeward side. Depending on the strength of the wind, jumping in the lee can be a very bad idea - canopy flight and landings will be turbulent and unpredictable, and wingsuit flights can also be affected.

Valley Winds Caused by Anabatic or Catabatic Flow

As the sun heats mountainsides and thermals lift, wind will be drawn through the valleys to replace the heating air. Valley wind is not always caused by atmospheric wind; the wind at altitude can be calm while, at the same time, solar heating is causing a strong valley breeze. This is an important distinction.

(At Left) Building induced turbulence, side view. Wind compresses at top edge, turbulates over the top and also behind. Turbulence also extends to ground level, and would appear as illustrated at right.

Valley “wind” can actually be caused by solar heating and is better referred to as the anabatic flow. Atmospheric wind may not be related to valley flow, although the two may influence each other. For instance, if the atmospheric wind depicted in this figure were to change 90 degrees and orient itself to match the valley flow, then the valley flow could be positively influenced by the atmospheric wind, and would generally become stronger and more turbulent. Similarly, an atmospheric wind can combat or block an anabatic flow, and vice versa.

(At Right) Building induced turbulence, top view. Wind compresses at the edges and turbulates around the sides and also behind. Jumping buildings in wind is a bad idea. Wait for no wind.

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