Photogrammeter, 71
Pillar of light, 122
Platte River, 131
Precipitation, intensity of, 226
— measurement of, 97
— summer, 107
Pressure, actual and recorded, 47
— and altitude, 48
— atmospheric, 39
— barogram of, 45
— daily ranges of, 44
— diurnal changes, 44
— mean for January (map), 40
— — July (map), 42
— — over earth, 44
— measurement of, 39
— semi-diurnal. Mt. Vernon, 46
— units of, 39, 193
Prevailing westerlies, 50
Prudden, T. M. quoted, 132
Psychrometer, sling, 217
Rainbow, 122
Rain and visibility, 141
— drops, size of, 97
— insurance against, 107
Rainfall, annual (map), 98
— cyclonic storms, 100
— Pacific Coast of U. S., 99
— Torrid Zone, 99
— Western Europe, 99
Rain gauges, Ferguson, 230
— — Friez recording, 224
— — installation of, 229
— — Marvin recording, 223
— — pit, 229
— — Short and Mason, 225
— — tipping-bucket, 224
— — Weather Bureau, 222
Reed, W. B., quoted, 83
Return trade wind,
Roaring forties, 50
St. Elmo fire, 115
Santa Ana wind, 55
Saturation, 6, 214
Scud, 81
Shaw, Sir Napier, quoted, 137, 188
Simoon, desert, 55
— electrical effects, 109
Sleet, 103
Sling psychrometer, 217
Smith, J. Warren, quoted, 119
Smoke and cloud formation, 57
— and visibility, 142
Snow, 101
— effect on visibility, 141
Snowfall, distribution of, 102
— measurement of, 230
— of Pacific Coast, 230
Snowflakes, structure of, 101
— photography of, 102
Snow gauges, 231
Solar constant, 21
Sounding balloons, 57
Specific gravity, 15
Storm cards of hurricane, 155
Storms, anticyclonic, 152
— classified, 150
— cyclonic, 101, 149
— dust, 142, 163
— forecasts, 151
— form and dimensions of, 156
— hail, 105
— ice, 103
— probabilities, 157
— secondary, 158
Storm tracks of U. S. (map), 154
Stratosphere, 27
— humidity of, 28
— movement of air in, 57
Summer precipitation, 107
Sun pillar, 122
Sunshine in U. S. (map), 248
— measurement, 250
— results of, 251
Sunshine recorders, 242, 245
— — Campbell-Stokes, 246
— — Marvin, 247
photographic, 247
Temperature, absolute, 177
— and altitude, 26, 57
— and latitude, 29
— radiation, 36
— and wind, 35
