﻿F. 
  H. 
  Bigelow 
  — 
  International 
  Cloud 
  Work. 
  439 
  

  

  B.t.e. 
  per 
  100 
  meters 
  in 
  each 
  stage 
  were 
  computed 
  and 
  tabu- 
  

   lated. 
  The 
  work 
  was 
  so 
  arranged 
  as 
  to 
  deal 
  with 
  tlie 
  mean 
  

   normal 
  meteorological 
  elements 
  prevailing 
  in 
  each 
  of 
  the 
  12 
  

   months, 
  so 
  that 
  the 
  annual 
  variations 
  in 
  all 
  these 
  quantities 
  

   were 
  found. 
  Also 
  selected 
  cases, 
  as 
  of 
  the 
  towering 
  cumulo- 
  

   nimbus 
  clouds, 
  some 
  of 
  which 
  reach 
  to 
  14,000 
  meters, 
  were 
  

   computed 
  throughout. 
  The 
  details 
  are 
  so 
  instructive 
  that 
  

   several 
  of 
  the 
  computations 
  are 
  reproduced 
  in 
  full. 
  The 
  tops 
  

   of 
  the 
  lofty 
  cumulo-nimbus 
  give 
  a 
  temperature 
  of 
  —30° 
  or 
  —40° 
  

   C. 
  in 
  several 
  cases, 
  and 
  of 
  —59° 
  C. 
  in 
  one 
  high 
  cloud. 
  This 
  

   method 
  of 
  computing 
  the 
  temperature 
  at 
  the 
  top 
  of 
  lofty 
  

   clouds 
  is 
  a 
  welcome 
  addition 
  to 
  the 
  method 
  of 
  the 
  balloon 
  

   ascensions 
  for 
  determining 
  the 
  meteorological 
  elements 
  in 
  the 
  

   highest 
  strata, 
  since 
  the 
  clouds 
  may 
  be 
  considered 
  as 
  accurate 
  

   sounding 
  gauges. 
  The 
  mean 
  heights 
  of 
  the 
  stages 
  show 
  that 
  

  

  the 
  7 
  stage 
  begins 
  at 
  about 
  -- 
  = 
  0*0090 
  and 
  develops 
  as 
  a 
  

  

  wedge-shaped 
  space 
  up 
  to 
  a 
  thickness 
  of 
  about 
  500 
  meters 
  for 
  

  

  -o7= 
  0*0300. 
  In 
  this 
  the 
  hail 
  forms, 
  and 
  especially 
  in 
  summer 
  

  

  when 
  t^eji^ 
  have 
  large 
  values. 
  I 
  am 
  inclined 
  to 
  think 
  that 
  the 
  

   stratified 
  appearance 
  of 
  hail 
  stones 
  is 
  due 
  to 
  tlie 
  fall 
  through 
  a 
  

   series 
  of 
  these 
  7 
  spaces 
  alternating 
  with 
  warmer 
  /3 
  stages, 
  

   which 
  may 
  form 
  at 
  different 
  heights 
  in 
  the 
  congested 
  state 
  of 
  

   the 
  atmosphere 
  accompanying 
  thunder 
  storms, 
  rather 
  than 
  to 
  

   any 
  vertical 
  orbital 
  circuhition 
  such 
  as 
  Ferrel 
  suggested. 
  At 
  

   every 
  point 
  of 
  these 
  computations 
  the 
  checks 
  are 
  so 
  perfect 
  

   that 
  we 
  can 
  work 
  accurately 
  to 
  1 
  millimeter 
  of 
  pressure 
  and 
  to 
  

   0°*1 
  C. 
  temperature, 
  when 
  the 
  trial 
  approximations 
  are 
  

   repeated 
  two 
  or 
  three 
  times. 
  

  

  (3) 
  It 
  is 
  a 
  most 
  interesting 
  problem 
  to 
  determine 
  just 
  how 
  

   much 
  heat 
  must 
  be 
  added 
  to 
  an 
  ideal 
  adiabatic 
  atmosphere 
  to 
  

   produce 
  the 
  actual 
  atmosphere 
  in 
  the 
  several 
  levels. 
  Two 
  pre- 
  

   liminary 
  discussions 
  were 
  required 
  to 
  develop 
  this 
  subject. 
  

   The 
  first 
  was 
  to 
  determine 
  the 
  normal 
  distribution 
  of 
  tempera- 
  

   ture 
  as 
  observed 
  each 
  month 
  at 
  all 
  altitudes 
  up 
  to 
  16,000 
  

   meters. 
  For 
  this 
  purpose 
  all 
  the 
  available 
  results 
  of 
  balloon 
  

   ascensions 
  were 
  collected 
  and 
  discussed 
  by 
  tabular 
  and 
  graphic 
  

   methods, 
  involving 
  a 
  balanced 
  network 
  of 
  mutually 
  dependent 
  

   lines, 
  by 
  which 
  the 
  average 
  temperature 
  topography 
  was 
  made 
  

   up 
  to 
  that 
  elevation. 
  Upon 
  the 
  reliability 
  of 
  these 
  observa- 
  

   tions 
  and 
  this 
  method 
  of 
  treatment 
  the 
  accuracy 
  of 
  the 
  results 
  

   required 
  must 
  depend. 
  The 
  second 
  discussion 
  was 
  the 
  deter- 
  

   mination 
  of 
  the 
  mean 
  heights 
  of 
  the 
  several 
  types 
  of 
  clouds 
  

   from 
  the 
  stratus 
  to 
  the 
  cirrus 
  in 
  each 
  month 
  of 
  the 
  year. 
  This 
  

   was 
  found 
  by 
  means 
  of 
  the 
  theodolite 
  observations 
  at 
  Washing- 
  

   ton, 
  D. 
  C, 
  and 
  from 
  them 
  the 
  region 
  covered 
  annually 
  by 
  each 
  

  

  