Rudolf Geiger Robert H. Aron Paul Todhunter

The Climate Near the Ground

Rudolf Geiger Robert H. Aron Paul Todhunter

The Climate Near the Ground Fifth Edition

II Vlewag

The first four editions have been published in 1927,1942,1950, and 1961 under the title Das Klima der bodennahen Luftschicht © Vieweg, Braunschweig Two English language editions have been published in 1950 and 1961 under the title The Climate Near the Ground © Harvard University Press, Cambridge, Mass.

The fifth edition is based on the HUP edition of 1961.

Co-authors of the fifth edition:

Dr. Robert H. Aron Department of Geography Central Michigan University Mount Pleasant, MI 48859, USA

All rights reserved

Dr. Paul Todhunter Department of Geography University of North Dakota Grand Forks, ND 58202, USA

© Friedr. Vieweg & Sohn Verlagsgesellschaft mbH, Braunschweig / Wiesbaden, 1995 Softcover reprint of the hardcover 5th edition 1995

Vieweg is a subsidiary company of Bertelsmann Professional Information.

No part of this publication may be reproduced, stored in a retrieval system or transmitted, mechanical, by photocopying or otherwise, without prior permission of the copyright holder.

Printed on acid-free paper

ISBN-13: 978-3-322-86584-7 DOl: 10.1007/978-3-322-86582-3

e-ISBN-13: 978-3-322-86582-3

v

CONTENTS

IN COMMEMORATION OF RUDOLF GEIGER'S ONE HUNDREDTH ANNIVERSARY ........................................................................................................ IX

PREFACES ................................................................................................................. XII

INTRODUCTION ..................................................................................................... .

1. Microclimate and Research .. ...... ................ .................. ........ ............ .......... 1

I. EARTH'S SURFACE ENERGY BALANCE .................................................... 5 2. Physical Basis of the Earth's Radiation Balance ........................................ 5 3. Components ofthe Energy Balance and Their Importance ........................ 8 4. Radiation Balance of the Earth's Surface ................................................... 10 5. Longwave Radiation atNight ..................................................................... 19 6. The Laws of Energy Transport in the Ground ........ .................................... 27 7. Transport of Energy in the Atmosphere. Eddy Diffusion .......................... 33 8. Mixing Due to Friction and Convection ...... .................. .......... ........ ........... 35 9. Temperature Instability, Dissemination of Seeds, Dispersion of Air

Pollutants, and Effective Stack Height as Problems of Eddy Diffusion .... 39

II. THE AIR LAYER OVER LEVEL GROUND WITHOUT VEGETATION ...... 51

10. Normal Temperature Stratification in the Underlying Surface (the Ground)................................................................................................ 51

11. Temperature in the Lowest 100m of the Atmosphere................................ 63 12. The Unstable Sublayer and the Inversion Sublayer .................................... 69 13. Daytime Temperature of the Air Layer near the Ground ............................ 73 14. Nighttime Temperature of the Air Layer near the Ground.. ................ ........ 81 15. Distribution of Water Vapor above the Ground .......................................... 89 16. The Wind Field and the Influence of Wind near the Ground...................... 97 17. Distribution of Particulates and Trace Gases .................. .......... .................. 107 18. Optical Phenomena Occurring near the Ground ............ ................ ............. 118

VI Contents

III. INFLUENCE OF THE UNDERLYING SURFACE ON THE ADJACENT AIR LAYER .................................................................. 123

19. Soil Type, Soil Mixtures, Soil Tillage......................................... ................ 123 20. Ground Color, Surface Temperature, Ground Cover (Mulching)

and Greenhouses................. ........................................................................ 131 21. Soil Moisture and Ground Frost ................................................................. 143 22. The Air Layer above Small Water Surfaces. ............................................ ... 161 23. The Air Layer near the Water Surface of Lakes, Seas and Rivers .............. 171 24. The Air Layer near Snow and Ice ............................................................... 177

IV. FURTHER ANALYSIS OF THE ENERGY BALANCE .................................. 197

25. Basis and Methods of Evaluation ............................................................... 197 26. Results of Previous Energy Balance Measurements .. ........................ ... ...... 202 27. Advective Influences and Transitional Climates ........................................ 210 28. Remarks on Evaporation ............................................................................. 215

V. THE EFFECT OF LOW PLANT COVER ON THE SURFACE AIR LAYER ..................................................................... 223

29. Energy Balance and Temperature of Plant Components ............................. 224 30. Radiation, Eddy Diffusion, and Evaporation in a Low Plant Cover ........... 236 31. The Microclimate of Meadows and Grain Fields ....................................... 244 32. The Microclimate of Gardens, Potato Fields, and Vineyards ....... ... ........... 254

VI. FOREST CLIMATOLOGY .................................. ................................... ..... ... ... 259

33. Radiation in a Forest ... .... .......................................... ............. ....... ... .... ....... 259 34. Metabolism, Energy Storage and Wind in a Forest ......................... ...... ..... 272 35. Air Temperature and Humidity in a Forest ........ .................................... ..... 278 36. Dew, Rain, and Snow in a Forest .................... ........ ....... ........................ ..... 284 37. Microclimate at the Stand Edges ................................................................ 298 38. Further Problems Concerning the Local Climate of Forests ........ ........... .... 308 39. Climatic Influences of the Forest................................................................ 316

VII. THE INFLUENCE OF TOPOGRAPHY ON THE MICROCLIMATE ............ 327

40. Insolation on Various Slopes ..................................................... ................. 327 41. The Effect of Differing Amounts of Sunshine on Microenvironment ........ 337 42. Small-Scale Topographic Influences at Night

(Cold Air Currents, Frost Hollows) ............................................................ 346

Contents VII

43. Local Winds in Hilly and Mountainous Terrain ......................................... 353 44. The Climate of Various Slopes (Exposure Climate) ................................... 372 45. The Thermal Belt ........................................................................................ 382 46. Microclimate in the High Mountains .. ........... .......... ... .... ...... .... ..... ............. 393 47. The Microclimate of Caves............................................... .......................... 401

VIII. INTERRELATION OF ANIMALS AND HUMANS TO THE MICROCLIMATE ............................................................................... 407

48. Animal Behavior ......................................................................................... 408 49. Animal Dwellings ....................................................................................... 412 50. Bioclimatology. ........................................................................................... 417 51. Urban Climate............................................................................................. 421 52. Artificial Protection against Wind .............................................................. 431 53. Artificial Protection against Low Temperatures ......................................... 446

REFERENCES ........................................................................................................... 457

SYMBOLS ....... .......................................................................................................... 501

CONVERSION TABLE ............................................................................................. 504

AUTHOR INDEX ...................................................................................................... 505

SUBJECT INDEX ...................................................................................................... 515

IX

IN COMMEMORATION OF RUDOLF GEIGER'S ONE HUNDREDTH ANNIVERSARY

Rudolf Geiger was born on 24 August 1894 and died 22 January 1981. He was born into a family of scholars. His father Wilhelm Geiger, 1856-1943, was Professor of Iranian and In­dian Studies in Erlangen and in Munich. His brother Hans Geiger, 1882-1945, became fa­mous in the field of nuclear physics and for assisting in developing the Geiger-Muller coun­ter (Geiger counter) in 1928, in collaboration with E. W. Muller.

Rudolf Geiger attended a humanitarian gymnasium (secondary school) in Erlangen and later studied mathematics. His dissertation was entitled: Geodesy of India in Antiquity and in the Middle Ages. This was the same general area of study as his father. His father's research concentrated upon the arts and humanities, while Rudolf Geiger's concentrated on the math­ematical and natural science aspects of this field.

In 1920 R. Geiger became an x-ray physicist at the Women's Clinic, University of Erlan­gen. He was, however, forced to abandon this line of work because of anemia, resulting from his exposure to x-rays.

From 1920 until 1923 he worked as an assistant at the Institute of Physics, Technological University of Darmstadt. In Darmstadt, he became interested in meteorology. In 1923 he joined the recently established Meteorological Department at the Forestry Experimental Station in Munich, which was attached to the Bavarian Weather Service. At the experimental station, he wrote his initial papers on the climate of plants and the nature of the air layers near the surface. In 1927 he was invited by the faculty to become a member of the academic community in meteorology and climatology. In 1937 he became Professor (ordinarius) of Meteorology, Mathematics and Physics, and Director of the Institute of Meteorology and Physics at the University of Forestry in Eberswalde.

In 1948 he became Professor (ordinarius) and Chairman of the Institute of Meteorology and Forestry Research Station at the University of Munich. In 1958 he attained the rank of Professor Emeritus.

Rudolf Geiger conducted research in the microclimatology of the air layers near the sur­face. He showed that temperature and moisture of air, soil, and vegetation are all interde­pendent.

The Bavarian network of weather stations made available abundant observational data for the exploration of the air layers near the surface. The investigations were performed in wooded patches of the Ebersberger Forest and although the research was very basic, it soon proved to have practical application in the afforestation of stands which had been damaged by localized late-frosts.

x

From the beginning, Geiger's research focused on the problems, consequences, and pre­vention of frost damage, both in forests, and gardens. As a result of this research, he was able to offer practical advice dealing with the prevention and restoration of frost damage.

Within forests his analysis of the variation of meteorological variables and the difference between stands with uniform crowns as compared to those with irregular heights, paved the way to his classical work on the climate of forests. This research concentrated upon the dif­ference in the climate of the crown and trunk area in both coniferous and deciduous forests. He found that while the climate in the trunk zone is more uniform, the crown layer is the active zone in which the energy exchange between the surface below and the atmosphere above takes place.

Geiger's measurements in the Hokenkarfen Mountains in Wurtemberg contributed to the study and understanding of the effects of hills and slopes upon the local climate (topoclima­tology). Rudolf Geiger also studied the variations of solar radiation, wind, and precipitation in different settings.

This research was further expanded to include microclimatic investigations in forested mountain regions (Grosser Arber) and in the beech forests which cover the thermal belts on many hills. Today this research constitutes the basis for further research into forests. Geiger not only actively took part in the development of scientific knowledge throughout the world, but he was also able to influence many other researchers.

In 1930, he took part in an exploratory voyage to West Africa to measure high altitude winds in preparation for air traffic by blimps (Zepplin air-ships). He became very active in international meteorological organizations. His appointment in 1937 as Secretary to the Commission for Agricultural Meteorology increased his responsibilities and widened his sphere of influence.

In 1950, as a result of his international reputation and connections, he was invited by C. W Thornthwaite to visit his climatology laboratory at John Hopkins University in Seabrook, New Jersey. During this stay, he participated in several research projects and was a guest lecturer. C. W. Thornthwaite later returned Geiger's visit by visiting and collaborating with him in Munich.

Rufolf Geiger became a member of the Bavarian Academy of Science. In 1956, through the mediation of UNESCO, he was invited as a specialist in microclimatology to participate in a symposium on the climatology of arid regions in Canberra, Australia. For the benefit of his students, he took numerous pictures of typical cloud formation over the archipelago of Indonesia while flying to Australia.

Rudolf Geiger's research is characterized by the organization and integration of countless observations into a unified explanation of the workings and interrelationships of the various elements of the local climate. This fundamental research has many practical applications and is in use in commercial aspects of forest climatology. As A. Baumgartner suggested in Forst­archiv No. 35, 1965, that the most rational form of fundamental research is when it has ap­plications in the real world.

Geiger always presented the results of his research in a clear, precise and perceptual way. He was also an enthusiastic, inspiring, and exemplary teacher. He was a congenial person, had a calm disposition, and his personality exuded warm humanity. His considered, pro­found, and well thought out opinions fascinated not only his students, but everyone who had the good fortune to come into contact with him.

XI

In 1952 R. Geiger became a full member of the Bavarian Academy of Science. From 1958 to 1961 he functioned as Class Secretary and during the period from 1963-1965 as Secretary of the Commission for Glaciology. Rudolf Geiger received the following honors: in 1955, he became a member of the Leopoldina Academy in Halle; in 1959, he received the Bavarian Order of Merit; in 1964. he became an honorary member of the Agrometeorolog­ical Society of Japan and the Munich Meteorological Society; in 1968, he received an Hon­orary Doctorate in Natural Sciences from the University of Hohenheim; and in 1977, he re­ceive the Peter Lenne Gold Medal from the Goethe Foundation in Basle.

A complete index of his published research appeared in the Forstarchiv, No. 35, 1965, pp.l00-104.

XII

PREFACE FIFTH EDITION

Few scientific books ever written become recognized as classics within their field. Dr. Gei­ger's The Climate Near the Ground was such a book. Sometimes referred to as 'The Bible of Climatology', it trained an entire generation of climatologists, and was a standard reference work for environmental scientists concerned with the surface microclimate. It not only pre­sented the historical development of microclimatic understanding but also attempted to lead up to the current state of knowledge.

Although the last revision of the book was completed in 1960, a reading of that edition still reveals the depth and breadth of understanding, keen insight, and clarity of expression which made it such a revered work. It is our belief that The Climate Near the Ground still has much to offer the current generation of environmental scientists. It is for this reason that we have undertaken the current revision.

In updating this book, our goals remain the same as those of Rudolf Geiger, namely to develop a clear and vivid textbook for those who are just taking up the study of microclima­tology and, at the same time, to serve as a reference work for those already familiar with the subject. As did Rudolf Geiger, we have attempted to bring all the topics covered in this book up to the present state of knowledge and have suggested some areas where additional re­search might prove both beneficial and fruitful.

With the proliferation of literature since 1960 we are certain that we have missed many advances that should have been included. As we plan to continue in the updating of this book, we invite readers to send any materials that they feel relevant. We, in turn, promise to acknowledge not only all contributions used but also those who have taken the time to send us the material.

We have made a concerted effort to conform to the organization, writing style, system of notation, and symbols of the original version of the book. This was done in a desire to assist in making those familiar with previous editions of the book feel comfortable with the revi­sion.

In 1960 the International System of Units (SI) was adopted at the International Confer­ence of Weights and Measures, organized by the International Bureau of Weights and Meas­ures in Paris, as the world standard. Since that time the SI system has largely supplanted the cgs system upon which the last edition of the book was based. Since both the SI and cgs systems are in such wide use today, most readers will be familiar with each. An appendix listing unit conversions has been included to assist the reader when needed. We have also, for the most part, retained the notation and terminology used by Dr. Geiger even though al­ternate symbols and terms may be more commonly used at present. In order to assist the reader we have included alternative terms in parentheses following the first use of a term in the text.

XIII

In comparing this new edition with the previous edition, the reader will find that many of the diagrams and substantial portions of the text remain essentially unaltered. In many cases we have purposely not replaced older figures with more recent ones which show essentially the same features in order to provide the reader with a sense of the historical development of the field of microclimatology. The organizational structure of the book remains largely un­altered and the writing style remains qualitative in nature. Quantitative developments in the field since 1960, including theoretical micrometeorology, micrometeorological instrumenta­tion, numerical modelling, remote sensing and digital elevation models have not been pur­sued in depth in order to retain the qualitative approach of the original work.

Our goal was not to totally rewrite this book, but simply to update those portions that have become dated and add new findings or topics that are relevant. Despite this original goal, substantial changes have been made both in topics added or expanded and those that have been reduced or eliminated. In addition, because the original translators were very faithful to the text, we have changed the wording in many places in an attempt to make the text read more smoothly.

We offer this revision in the hope that this important work remains as a useful reference in the field.

We wish to acknowledge I-Ming Aron for her time and many helpful suggestions. We also wish to thank Central Michigan University for its generous support in awarding Robert Aron a sabbatical to work on this book, and for furnishing financial assistance for typing and graphic arts.

Our thanks also extend to Dennis Pompilius at Central Michigan University Graphic Arts and our typist, Martha Brian.

Robert Aron, Ph.D. Department of Geography Central Michigan University Mt. Pleasant, MI, U.S.A. E-mail: Robert.H.Aron@cmich.edu

Paul Todhunter, Ph.D. Department of Geography University of North Dakota Grand Forks, ND, U.S.A. E-mail: UDI78101@NDSUVMI September 1994

XIV

PREFACE TO THE FOURTH EDITION

Anyone who merely turns the pages of this new edition will find that 48 percent of the fig­ures are familiar to him from the third edition. But whoever reads it will discover that no three consecutive pages of text have been transferred unaltered. The enormous development that has taken place since 1950, particularly the surprising extension in the practical applica­tions of micrometeorology, have made it necessary to rewrite the book.

In producing this work, I had in mind two aims which were linked more closely to each other than I had at first dared to hope. The new edition was to be a clear and vivid textbook for those who were just taking up the study of microclimatology, and at the same time a ref­erence work for those already familiar with the subject. For the fIrst task, I had in mind the students who would recoil with horror at the insurmountable barrier of an apparently unlim­ited and ever-increasing pile of literature and thus were in need of assistance. In addition, I was thinking of colleagues working in related sciences, who have no time to study our liter­ature. And finally, but not least important, I was also thinking of all who work on the land, in forests and gardens, the architects, geographers, country planners, entomologists, doctors, transportation engineers, and others who - without having studied much physics - are anx­ious to acquire a knowledge of the rational physical principles governing the meteorologic laws that they have to put into practice. For the benefit of all these, I have at all times made renewed efforts to state the facts in the simplest and most uncomplicated manner possible. I have also tried at all times to improve the style so that the reader would be able to go on his way lightly. The extent to which I have been successful in providing genuine help to the reader remains to be seen.

The book should, in addition, everywhere lead up to the present day status in research and thus be of assistance to those already familiar with the subject. To stay within the re­quired limits of space permitted, only brief references are made to results that pointed the way to the future. The novice will easily pass over these; whereas to the initiated they pro­vide access to the literature on the subject.

lowe a special debt of gratitude to my university colleague, Dr. Gustav Hofmann, who read the finished manuscript. The lively discussions that followed resulted in the introduction of many improvements in the book.

I would like, further, to thank all those who assisted me by sending reprints of their works. Much came to my knowledge only by this means. Such assistance is indispensable in a technical field that has so many contacts with neighboring sciences. It is precisely the rep­resentatives of these adjacent fields of knowledge whom I would ask most urgently to bring to my notice any of the deficiencies and gaps in treatment, which are unavoidable with the present day scope and tempo of research in microclimate.

xv

During my work on the new edition, it became clear to me why, in spite of the ever-swell­ing flood of published papers, the number of usable textbooks is increasing much more slow­ly. In drafting almost every chapter, I could feel the spirit of a cherished colleague, at home or abroad, looking over my shoulder, and it seemed to me that he was more fitted to write just this chapter than I was. Then came the feeling of suffocation under the weight of good new literature, and the anxiety that the first chapter would be out of date before the last one could be finished. However, I was able to bear these tensions daily for three years, because without useful signposts no one can find his way in the labyrinth of science. If I have been able to point the way to a few, this will be my best reward for all the pains taken.

Munich-Pasing, November 1960 Perlschneiderstrasse, 18

RUDOLF GEIGER

XVI

PREFACE TO THE FIRST EDITION

I was introduced to microclimatology by Professor A. Schmauss. He put me in charge of the organization and direction of the Bavarian special network for investigation of the air layer near the ground. Later I also had to make two extensive open-air investigations in forest meteorology. I had a good opportunity to get in closer touch with people dealing in forestry, moor cultivation, and agriculture. Thus I became acquainted with the difficulties in the prac­tical application of the results of climatological research. The problem of application is in­deed not new. While a systematic study has not been undertaken as yet, many valuable con­tributions have already been made, as, I hope, this book will demonstrate. This book is in­tended for the practical person who has neither time nor opportunity to look for the available papers from the vast meteorological literature. When, therefore, I was invited to write a "Climate near the Ground." I was glad of the opportunity to attempt a first survey of rnicro­climatological problems. This is the best way for me to thank people for the manifold sug­gestions that I have received from them, particularly those with a special interest in forestry. It is also a pleasure to express here my sincerest thanks to Professor Schmauss for his con­stant and unselfish furtherance of my work.

RUDOLF GEIGER Munich, July 1927