﻿F. 
  W. 
  Very 
  — 
  Solar 
  Radiation. 
  615 
  

  

  amount 
  of 
  violet 
  radiation 
  to 
  be 
  relatively 
  small 
  were 
  days 
  of 
  

   many 
  spots, 
  while 
  the 
  one 
  on 
  which 
  they 
  found 
  it 
  relatively 
  

   large 
  was 
  a 
  day 
  of 
  exceedingly 
  few 
  spots" 
  (op. 
  cit., 
  p. 
  100). 
  

   More 
  extensive 
  observations 
  would 
  be 
  desirable, 
  but 
  the 
  

   hypothesis 
  is 
  plausible. 
  

  

  If 
  the 
  portion 
  of 
  energy 
  in 
  the 
  shorter 
  waves, 
  cut 
  off 
  by 
  the 
  

   scattering, 
  be 
  handed 
  on 
  to 
  more 
  elevated 
  solar 
  " 
  dust," 
  and 
  

   again 
  emitted 
  as 
  an 
  equivalent 
  radiation 
  of 
  longer 
  wave-length 
  

   from 
  particles 
  at 
  a 
  lower 
  temperature, 
  the 
  solar 
  radiation 
  at 
  

   epochs 
  of 
  sun-spot 
  maxima, 
  or 
  whenever 
  the 
  coronal 
  and 
  other 
  

   "dust" 
  is 
  most 
  prevalent 
  (as 
  after 
  unusual 
  development 
  of 
  

   prominences), 
  is 
  richer 
  in 
  long 
  waves 
  and 
  passes 
  more 
  readily 
  

   through 
  the 
  earth's 
  atmosphere, 
  whence 
  the 
  earth's 
  tropical 
  

   regions 
  (where 
  the 
  chief 
  thermal 
  effects 
  are 
  to 
  be 
  expected) 
  

   receive 
  a 
  larger 
  accession 
  of 
  heat 
  at 
  sun-spot 
  maxima, 
  as 
  several 
  

   meteorologists 
  have 
  maintained. 
  Dr. 
  Humphreys 
  arrives 
  at 
  

   the 
  opposite 
  conclusion, 
  and 
  owing 
  to 
  the 
  great 
  importance 
  

   which 
  he 
  attaches 
  to 
  the 
  ozone 
  absorption 
  bands 
  in 
  the 
  earth's 
  

   atmosphere, 
  he 
  favors 
  the 
  supposition 
  that, 
  although 
  more 
  

   ozone 
  may 
  be 
  produced 
  in 
  high 
  latitudes 
  at 
  sun-spot 
  maxima 
  

   on 
  account 
  of 
  increased 
  electric 
  discharges 
  in 
  the 
  upper 
  air 
  dur- 
  

   ing 
  auroral 
  displays, 
  less 
  ozone 
  is 
  formed 
  in 
  the 
  upper 
  air 
  of 
  the 
  

   tropics 
  at 
  this 
  time 
  because 
  the 
  sun's 
  ultra-violet 
  rays 
  are 
  

   diminished 
  ; 
  and 
  on 
  the 
  whole 
  the 
  earth 
  is 
  then 
  cooler, 
  because 
  

   more 
  telluric 
  radiation 
  escapes 
  in 
  the 
  region 
  of 
  the 
  spectrum 
  

   covered 
  by 
  the 
  ozone 
  bands 
  near 
  10 
  \i. 
  My 
  reasons 
  for 
  not 
  

   accepting 
  the 
  role 
  which 
  he 
  assigns 
  to 
  ozone 
  as 
  the 
  most 
  potent 
  

   controller 
  of 
  terrestrial 
  temperature 
  may 
  be 
  seen 
  in 
  an 
  article 
  

   on 
  " 
  Sky 
  Radiation 
  and 
  the 
  Isothermal 
  Layer."* 
  

  

  An 
  increase 
  in 
  solar 
  radiation 
  does 
  not 
  cause 
  higher 
  tempera- 
  

   tures 
  over 
  all 
  the 
  earth, 
  but 
  the 
  one 
  cause 
  leads 
  to 
  opposite 
  

   effects 
  in 
  diverse 
  regions. 
  An 
  average 
  of 
  terrestrial 
  thermal 
  

   fluctuations 
  may 
  give 
  either 
  a 
  positive 
  or 
  a 
  negative 
  residual 
  

   according 
  to 
  the 
  preponderance 
  of 
  stations 
  in 
  one 
  or 
  the 
  other 
  

   of 
  the 
  opposing 
  classes, 
  and 
  the 
  actual 
  solar 
  influence 
  stands 
  a 
  

   good 
  chance 
  of 
  remaining 
  either 
  unrecognized, 
  or 
  greatly 
  

   underrated 
  in 
  climatological 
  summaries. 
  

  

  In 
  Abbot's 
  work 
  on 
  " 
  The 
  Sun 
  " 
  we 
  read 
  : 
  " 
  The 
  earth's 
  sur- 
  

   face 
  air 
  temperature 
  is 
  on 
  the 
  whole 
  lower 
  at 
  sun-spot 
  maximum 
  

   than 
  at 
  sun-spot 
  minimum 
  ,"f 
  and 
  this 
  .conclusion 
  is 
  reiterated 
  

   on 
  page 
  405 
  : 
  " 
  The 
  change 
  of 
  temperature 
  of 
  the 
  earth 
  seems 
  

   to 
  indicate 
  that 
  the 
  sun's 
  radiation 
  is 
  at 
  a 
  maximum 
  when 
  sun 
  

   spots 
  are 
  fewest" 
  This 
  remark 
  is 
  made 
  in 
  connection 
  with 
  an 
  

   allusion 
  to 
  the 
  variability 
  of 
  Mira 
  Ceti 
  which 
  " 
  suggests 
  the 
  

   solar 
  variability 
  associated 
  with 
  sun-spots," 
  but 
  which 
  is 
  here 
  

  

  * 
  This 
  Journal 
  (4), 
  vol. 
  xxxv, 
  pp. 
  369-388, 
  April, 
  1913. 
  

   fP. 
  190. 
  

  

  