﻿232 
  Mr. 
  E. 
  M. 
  Deeley 
  on 
  

  

  The 
  low 
  pressure 
  and 
  inward 
  flow 
  of 
  surface 
  currents 
  are 
  

   maintained 
  by 
  the 
  buoyancy 
  of 
  the 
  warm 
  air 
  of 
  the 
  strato- 
  

   sphere, 
  in 
  which 
  there 
  is 
  also 
  a 
  cyclonic 
  circulation. 
  

  

  According 
  to 
  this 
  conception 
  a 
  cyclone 
  is 
  the 
  result 
  of 
  the 
  

   outward 
  flow 
  of 
  a 
  volume 
  of 
  heated 
  air 
  in 
  the 
  upper 
  portion 
  

   of 
  the 
  stratosphere, 
  an 
  inflow 
  near 
  the 
  earth's 
  surface, 
  and 
  a 
  

   slight 
  bodily 
  lifting 
  of 
  the 
  mass 
  of 
  air 
  between. 
  

  

  A 
  section 
  of 
  the 
  atmosphere 
  between 
  the 
  equator 
  and 
  the 
  

   pole 
  shows 
  the 
  same 
  temperature 
  distributions 
  as 
  does 
  a 
  

   cyclone. 
  Fig. 
  7 
  is 
  a 
  generalized 
  section 
  from 
  the 
  pole 
  to 
  the 
  

   equator 
  showing 
  what 
  would 
  appear 
  to 
  be 
  the 
  temperature 
  

   distribution 
  in 
  the 
  atmosphere, 
  as 
  revealed 
  by 
  observations 
  

   made 
  with 
  self-registering 
  pilot 
  balloons. 
  The 
  dotted 
  iso- 
  

   therms 
  are 
  purely 
  theoretical. 
  A 
  A 
  is 
  the 
  earth's 
  surface 
  

   and 
  the 
  dotted 
  line 
  B 
  B 
  the 
  lower 
  surface 
  of 
  the 
  stratosphere. 
  

   Fig. 
  7, 
  it 
  will 
  be 
  noticed, 
  closely 
  resembles 
  the 
  left 
  side 
  of 
  

   the 
  cyclone 
  shown 
  in 
  fig. 
  6. 
  Over 
  both 
  low-pressure 
  areas 
  

   there 
  are 
  masses 
  of 
  warm 
  air 
  in 
  the 
  stratosphere. 
  

  

  It 
  is 
  only 
  possible 
  to 
  obtain 
  an 
  idea 
  of 
  the 
  temperatures 
  of 
  

   the 
  upper 
  portions 
  of 
  the 
  stratosphere 
  by 
  a 
  study 
  of 
  the 
  atmo- 
  

   spheric 
  pressure 
  on 
  the 
  earth's 
  surface 
  and 
  the 
  temperature 
  

   of 
  the 
  troposphere. 
  The 
  troposphere 
  has 
  been 
  sounded 
  in 
  

   many 
  places, 
  and 
  its 
  temperature 
  is 
  fairly 
  well 
  known 
  at 
  

   several 
  latitudes. 
  In 
  constructing 
  the 
  diagram 
  fig. 
  7 
  the 
  

   temperatures 
  of 
  the 
  troposphere, 
  as 
  ascertained 
  for 
  Batavia, 
  

   Milan, 
  Pavia, 
  England, 
  and 
  Pavlovsk, 
  have 
  been 
  plotted, 
  

   and 
  the 
  isotherms 
  drawn 
  in. 
  Comparing 
  the 
  variations 
  in 
  

   weight 
  of 
  the 
  air 
  columns 
  at 
  these 
  places 
  resulting 
  from 
  their 
  

   different 
  temperatures 
  with 
  the 
  actual 
  barometric 
  readings, 
  it 
  

   is 
  clear 
  that 
  a 
  ridge 
  of 
  cold 
  air 
  in 
  the 
  stratosphere 
  must 
  encircle 
  

   the 
  earth 
  at 
  latitude 
  30° 
  north 
  and 
  south 
  of 
  the 
  equator, 
  

   and 
  there 
  is 
  a 
  trough 
  of 
  heated 
  air 
  in 
  the 
  upper 
  atmosphere 
  

   over 
  the 
  equatorial 
  regions, 
  and 
  a 
  basin 
  of 
  hot 
  air 
  over 
  each 
  

   pole. 
  Isotherms 
  have 
  been 
  drawn 
  in 
  the 
  stratosphere 
  to 
  

   illustrate 
  this 
  ; 
  but 
  to 
  obtain 
  an 
  accurate 
  representation 
  

   of 
  the 
  variation 
  of 
  temperature 
  further 
  observations 
  are 
  

   necessary. 
  

  

  The 
  high-pressure 
  ridge 
  is 
  rather 
  a 
  string 
  of 
  anticyclones 
  

   and 
  the 
  north 
  polar 
  basin 
  has 
  two 
  minima, 
  one 
  over 
  the 
  North 
  

   Atlantic 
  and 
  the 
  other 
  over 
  the 
  Behring 
  Sea. 
  The 
  South 
  

   Polar 
  Continent 
  is 
  the 
  centre 
  of 
  one 
  great 
  cyclone 
  due 
  to 
  the 
  

   heated 
  basin 
  of 
  air 
  in 
  the 
  stratosphere. 
  Were 
  it 
  not 
  for 
  the 
  

   powerful 
  action 
  of 
  this 
  basin, 
  anticyclonic 
  conditions 
  would 
  

   prevail 
  there. 
  

  

  