Chapter II: Introduction: vii

I ATMOSPHERES OF THE EARTH, THE SUN, AND THE PLANETS 1

II A SYNOPTIC PICTURE OF THE AIR 7

III EXPLORATIONS OF THE ATMOSPHERE 18

IV EARTH’S FOUR ATMOSPHERES 29

V LIGHT, HEAT, AND TEMPERATURE 48

VI THE ADVANTAGE OF TAKING WEATHER OBSERVATIONS AND
APPLYING THEM TO ONE’S PERSONAL NEEDS 64

VII FROST 85

VIII WIND AND PRESSURE OF THE GLOBE 98

IX HOW TO FORECAST FROM THE DAILY WEATHER MAP 112

X CLIMATE 161

XI HOW CLIMATE IS MODIFIED AND CONTROLLED 188

XII CIVILIZATION FOLLOWS THE STORM TRACKS 213

XIII HAS OUR CLIMATE CHANGED? 225

XIV CLIMATES FOR HEALTH AND PLEASURE 245

XV CONDENSATION 282

XVI DEVELOPMENT OF THE AMERICAN WEATHER SERVICE 291

INDEX 307

LIST OF FIGURES

Instrument Shelter (Figure 4) _Frontispiece_

FIGURE PAGE

1. Winter and Summer Vertical Temperature Gradients, in
degrees Centigrade and Fahrenheit 12

2. Showing light from lamp a passing into dust-free air
at _b_, and passing out at _c_ without illuminating
the interior 46

3. Standard Weather Bureau Kite 64

5. Comparison of the Thermometer Scales 67

6. Dry and Wet Bulb Thermometers 68

7. Mercurial Barometer 78

8. Continuous records of the temperature from 4 P.M.
to 9 A.M. 87

9. Continuous records of the temperature 5 feet and 35
feet above ground on a tower in a pear orchard 95

10. Average dates of last killing frost in Spring 96

11. Average dates of first killing frost in Fall 97

12. Trade wind circulation 99

13. Average surface winds and pressure of the globe 102

14. How winds would blow into a cyclone on a non-rotating
earth 108

15. Deflection of wind due to earth’s rotation 109

16. Annual, summer, and winter wind velocities with
altitude 110

17. Tornado Cloud 145

18. The St. Louis Tornado of May 27, 1896, Shot a Pine
Scantling through the Iron Side of the Eads Bridge 147

19. The St. Louis Tornado of May 27, 1896, Shot a Shovel
Six Inches into the Body of a Tree 147

20. The St. Louis Tornado Drove Straws One half Inch
into Wood 149

21. Equinoxes, March 21 and September 22 163

22. Summer Solstice, June 21 164

23. Winter Solstice, December 21 164

24. Winter and Summer Solstices, and the Equinoxes 165

25. As angle of incidence decreases from 90° to 10° the
heat received on upper end of blocks is spread
over greater area at bottom, and its temperature
diminished 165

26. Altitude attained by Sun at midday and length of its
track above the horizon at the Summer and Winter
Solstices and at the two Equinoxes 167

27. Summer day and Summer night temperatures in the same
narrow valley 204

28. Average Monthly Temperature and Rainfall of Typical
Places in North America 207

29. Average Monthly Temperature and Rainfall of Typical
Places in the Old World 208

30. Changes in Climate in California during the Christian
Era 237

31. Snow Crystals 286

LIST OF CHARTS

CHART PAGE

1. High and Low Centers of Action and Prevailing Winds
of the Globe for July 99

2. High and Low Centers of Action and Prevailing Winds
of the Globe for January 100

3. Winter Storm, December 15, 1893, 8 A.M. 114

4. Winter Storm, December 15, 1893, 8 P.M. 116

5. Winter Storm, December 16, 1893, 8 A.M. 118

6. Cold Wave Zones, March to November. Amount of Fall
and Verifying Limit 127

7. Cold Wave Zones, December, January, and February.
Amount of Fall and Verifying Limit 128

8. Lowest Temperatures in the United States, 1871-1913 129

9. Number of Cold Waves, 1904-1914, Inclusive 130

10. Storm Tracks for August for Ten Years 132

11. Storm Tracks for February for Ten Years 134

12. Average Maximum Temperature for July 195

13. Ocean Currents 196

14. Mean Annual Isotherms 200

15. Normal Wind Direction and Velocity for January and
February 202

16. Normal Wind Direction and Velocity for July and
August 204

17. Map of Climatic Energy 221

18. Density of Population in the United States, 1910 222

THE NEW AIR WORLD