Encyclopedia of Weather and Climate

825 Pages·2007·19.83 MB·English

by  Michael Allaby

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ENCYCLOPEDIA OF
weather and climate
Revised Edition
Volume I
A–o
michael allaby
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ENCYCLOPEDIA OF WEATHER AND CLIMATE, Revised Edition
Copyright © 2007, 2002 by Michael Allaby
All rights reserved. No part of this book may be reproduced or utilized in any form or by any
means, electronic or mechanical, including photocopying, recording, or by any information
storage or retrieval systems, without permission in writing from the publisher.
For information contact:
Facts On File, Inc.
An Imprint of Infobase Publishing
132 West 31st Street
New York NY 10001
ISBN-10: 0-8160-6350-8 (set)
ISBN-13: 978-0-8160-6350-5 (set)
Library of Congress Cataloging-in-Publication Data
Allaby, Michael.
Encyclopedia of weather and climate / [Michael Allaby].—Rev. ed.
p. cm.
Includes bibliographical references and index.
ISBN 0-8160-6350-8 (set)—
ISBN 0-8160-6348-6 (v.1)—ISBN 0-8160-6349-4 (v. 2) 1. Meteorology—
Encyclopedias. 2. Climatology—Encyclopedias. I. Title.
QC854.A452007
551.603—dc22 2006018295
Facts On File books are available at special discounts when purchased in bulk quantities for
businesses, associations, institutions, or sales promotions. Please call our Special Sales
Department in New York at [phone] or [phone].
You can find Facts On File on the World Wide Web at http://www.factsonfile.com
Text design by Joan M. McEvoy
Cover design by Salvatore Luongo
Illustrations by Richard Garratt
Photo research by Tobi Zausner, Ph.D.
Printed in the United States of America
VB Hermitage 10 9 8 7 6 5 4 3 2 1
This book is printed on acid-free paper.
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C
ONTENTS
Acknowledgments
v
Introduction
vi
Abbreviations and Acronyms
ix
Entries A–O
1
APPENDIXES
I. Biographical Entries
573
II. Tropical Cyclones and Tropical Storms
655
III. Chronology of Tornadoes
669
IV. Laws, Regulations, and International Agreements
673
V. The Geologic Timescale
675
iii
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VI. Ocean Currents
677
VII. Pliocene, Pleistocene, and Holocene Glacials and
Interglacials
691
VIII. SI units and conversions
693
IX. Chronology of Disasters
695
X. Chronology of Discoveries
703
Bibliography and Further Reading
709
Web Sites
711
Index
I-1
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A
CKNOWLEDGMENTS
My friend Richard Garratt drew all of the maps, diagrams, and other line
drawings in this encyclopedia. Richard and I have collaborated on many
projects, spanning more years than either of us cares to count. He has a
genius for translating my crude sketches into accurate and attractive illus-
trations. As always, I am deeply grateful to him.
There were not many photographs in the first edition of the encyclo-
pedia, but we decided to include them in this edition. I drew up a long
list of topics I thought might benefit from a photograph and sent the list
to Tobi Zausner. With great perseverance and unfailing good humor she
gathered together the pictures you will see here. Without Tobi’s help this
would be a less informative book than it is, and one less pleasing to
the eye.
Finally, I must thank my friends at Facts On File. In particular,
I would like to thank my editor, Frank K. Darmstadt, for his patience,
wisdom, and the kindly interest he always shows in the well-being
of his author and for the polite interest he shows in the current loca-
tion of the text he was supposed to have received weeks or months ago.
Appreciation also goes to his assistant, Alana Braithwaite, for going
through this huge manuscript and getting all of its elements in order for
production to take over.
This work is not a compilation of entries written by contributors. I
wrote all of the entries myself. The consequence is that any mistakes that
have escaped Frank’s eagle eye are entirely my own work. So are the facts
I got right, of course.
v
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I
NTRODUCTION
Everyone has an interest in the weather, and in recent years that interest
has intensified. Climates always change over long periods. The weather
the world experiences today is different from that of the Little Ice Age of
the 17th century and of the Middle Ages, when the climate was warm and
England was a major wine producer. Today, though, there are fears that
the climate may be changing faster than it has done for thousands of years
and that the gases released into the air from cars, factories, domestic fires,
power stations, farming, and forest clearance may be accelerating that
change. This concern is now driving climatic research.
The climate of a place or of the world is the average weather that it
experiences over a long period. On a shorter timescale, the day-to-day
weather affects everyone. Those who set off for school or work without
a coat or umbrella may get a soaking if they forget to check before leav-
ing home whether it is raining. In winter, when snow and ice are likely,
drivers should check before setting off whether the roads are safe and, if
they are, whether conditions are likely to deteriorate. Misjudgments can
be serious. Snowfalls can make roads impassable, marooning people in
their cars where the low temperature can kill.
Some people need to know about the coming weather in more detail.
Fishermen must know whether it will be safe for them to put to sea.
Sailors of all kinds need to know whether they are sailing into a severe
storm and, if so, how to avoid it. Pilots need to know the speed and
direction of the winds along the routes they plan to fly. These determine
the time the journey will take and the amount of fuel the aircraft will
consume.
Extreme weather such as tornadoes, tropical cyclones, and floods can
cause widespread devastation. Lives can be saved and damage to prop-
erty minimized if communities receive adequate warning and respond
appropriately. The warning may be broadcast on behalf of the govern-
ment by a radio or television station, but it is based on information sup-
plied by meteorologists—the scientists who study, monitor, and forecast
the weather.
There are also less immediate ways in which the weather affects
people. Fine growing weather across the farmlands of the nation, with
rain when it is needed and sunshine to ripen the crops, produces heavy
crop yields. Food is abundant, and when a commodity is abundant its
vi
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Introduction vii
price falls. So fine weather can make food cheaper. In the same way, bad
weather can lead to low yields and higher prices. Changes in food prices
may make the difference between relative prosperity and hardship for the
poorest members of society, and in some parts of the world bad weather
may lead to famine, in which people die.
Mild winters reduce heating bills. People do not need so much ener-
gy to warm their homes as they do when the winter is hard. This makes
a difference to living costs, and it also has environmental consequences.
Burning fossil fuels—coal, oil, or gas—to generate electrical power, or
directly for space heating, water heating, and cooking, releases by-prod-
ucts of combustion into the air. Some of these, such as sulfur dioxide,
carbon monoxide, and unburned hydrocarbons, cause pollution.
My own interest in weather and climate began many years ago. For
a short time I was a military pilot, so I was compelled to observe the
weather and to respect it. I learned then that bad weather can kill and
that it pays to listen to the weather forecast. More recently, my inter-
est has developed from my studies of the environmental sciences. These
include the atmospheric sciences of climatology and meteorology as well
as the historical disciplines such as paleoclimatology, which is the study
of the climates of the distant past.
Several years have passed since the previous edition of the
Encyclopedia of Weather and Climate was published. Research in the
atmospheric sciences is intense, and so much has happened during those
years that a new edition seemed advisable. This edition contains a num-
ber of new entries, but almost all of the entries from the earlier edition
have been revised. Some have been expanded and others modified to take
account of recent discoveries about the atmosphere and the way it works.
The preparation of a new edition also made it possible to alter the
overall structure of the encyclopedia. Many of the shorter entries in the
earlier edition have been assembled into longer essays in this edition.
Some short entries remain, but this edition contains a smaller number of
much longer essays that incorporate all the information from the earlier
edition—and often more.
Certain categories of entry have been removed altogether from the
main body of the encyclopedia and are contained in 10 appendixes. The
appendixes contain biographical notes on more than 120 individual sci-
entists, as well as lists of the most severe tropical cyclones and tropi-
cal storms, tornadoes, weather disasters, and milestones in atmospheric
research. The principal ocean currents are also listed alphabetically and
described in an appendix. I hope that placing this material in appendixes
makes it more easily accessible.
The main body of the encyclopedia contains entries describing pro-
cesses such as cloud formation, atmospheric phenomena such as rain-
bows, and some of the techniques and instruments that are used to study
the atmosphere, as well as the units of measurement that scientists use.
They also explain the classification systems that are used for climate
types, winds, and clouds.
The weather we experience is local. It may be raining on one side
of a hill and fine on the other side. This means that from time to time
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viii Introduction
many places experience weather conditions different from those in the
surrounding region, and the local conditions usually have local names.
Winds, in particular, acquire local names. The chinook, Santa Ana, mis-
tral, harmattan, bora, and sirocco are just a few of the local names for
winds that people in certain places welcome or dread. The encyclope-
dia lists some of these, in entries on local weather and local winds, and
explains each type and where it occurs.
Before there were weather stations, orbiting satellites, and power-
ful computers to produce weather forecasts, people had to rely on their
experience and the signs they could read, or thought they could read, in
the sky and in the natural world around them. Over centuries these expe-
riences accumulated as weather lore, comprising sayings, rhymes, and
references to clouds, plants, and animals. Some of these are also included
here, in an entry on weather lore.
Small capital letters (like this) used within entries act as cross-refer-
ences, indicating terms for which there are full entries.
Items for further reading and relevant Web sites are listed at the end
of the entries to which they relate. They are also listed at the end of the
encyclopedia.
Finally, a note on the units of measurement used here. Many scientif-
ic disciplines use special units to describe quantities that are relevant only
within those disciplines. Atmospheric chemists, for example, use Dobson
units to measure the concentration of atmospheric gases, especially of
ozone. Apart from such specialist units, all scientists work in SI units. SI
stands for Système International d’Unités (International System of Units).
The meaning of individual units (including Dobson units) is explained in
the entry “units of measurement”; SI units are listed with their abbrevia-
tions and, where appropriate, conversions to customary units.
Meteorologists measure air pressure in pascals, but weather forecast-
ers often use the older unit, the millibar (1 millibar = 100 pascals).
Temperatures are reported in degrees Celsius (°C) or in kelvins (K),
depending on the context. In this encyclopedia, temperatures are given in
degrees Fahrenheit (°F) with °C in parentheses.
Rainfall is always reported in millimeters and never in centimeters.
There are two reasons for this. The first is to avoid decimal fractions so
far as is possible by using a small unit. The second is to avoid the confu-
sion that might occur if two units were used, one of which is 10 times
bigger than the other. In all entries in this Encyclopedia of Weather and
Climate, Revised Edition, rainfall is given in inches with millimeters in
parenthesis.
I hope you enjoy wending your way through the highways and
byways of atmospheric science as you explore the processes that generate
our weather. Writing the encyclopedia was fun. I hope it is fun to use.
—Michael Allaby
Tighnabruaich
Argyll, Scotland
www.michaelallaby.com
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