﻿Mean 
  Annual 
  Temperature 
  Variation. 
  403 
  

  

  just 
  as 
  if 
  the 
  station 
  had 
  been 
  shifted 
  into 
  another 
  climate, 
  sim- 
  

   ilar, 
  but 
  colder 
  than 
  it 
  ought 
  to 
  be 
  during 
  the 
  summer, 
  and 
  

   warmer 
  than 
  it 
  ought 
  to 
  be 
  during 
  the 
  winter. 
  

  

  The 
  annual 
  variation 
  proceeds 
  by 
  steps. 
  The 
  steps 
  of 
  ascent, 
  

   occurring 
  while 
  the 
  temperature 
  is 
  decreasing, 
  correspond 
  to 
  

   similar 
  steps 
  of 
  descent 
  observed 
  during 
  the 
  other 
  half 
  of 
  the 
  

   year. 
  

  

  Each 
  successive 
  stage 
  marks 
  the 
  passage 
  from 
  one 
  phase 
  to 
  

   another. 
  

  

  In 
  the 
  preceding 
  example 
  the 
  annual 
  variation 
  is 
  composed 
  

   of 
  three 
  phases. 
  

  

  This 
  opinion 
  seems 
  never 
  to 
  have 
  been 
  advanced 
  and 
  it 
  is 
  

   astonishing 
  to 
  notice 
  that 
  even 
  the 
  fact 
  of 
  the 
  existence 
  of 
  

   steps 
  during 
  the 
  autumn, 
  corresponding 
  to 
  the 
  steps 
  of 
  the 
  

   spring, 
  has, 
  so 
  far 
  as 
  I 
  know, 
  practically 
  attracted 
  no 
  attention; 
  

   though 
  the 
  frequently 
  recurring 
  temperature 
  anomalies 
  for 
  

   given 
  dates, 
  in 
  May 
  and 
  June, 
  have 
  been 
  very 
  extensively 
  

   studied. 
  

  

  Researches 
  of 
  particular 
  interest 
  concerning 
  these 
  anomalies 
  

   are 
  those 
  of 
  G. 
  Hellmann,* 
  W. 
  v. 
  Bezold,f 
  Ch. 
  Dufour,J 
  W. 
  

   Marten, 
  § 
  R. 
  Gautier| 
  and 
  K. 
  Almstedt^f 
  

  

  The 
  principal 
  results 
  gained 
  by 
  these 
  authors 
  may 
  be 
  sum- 
  

   marized 
  as 
  follows 
  : 
  

  

  (1). 
  The 
  temperature 
  depressions 
  are 
  not 
  strictly 
  bound 
  to 
  

   given 
  dates. 
  Their 
  occurrence 
  varies 
  slightly 
  from 
  year 
  to 
  

   year, 
  but 
  on 
  the 
  average, 
  in 
  Central 
  Europe, 
  the 
  llth-15th 
  of 
  

   May 
  and 
  the 
  4th-8th 
  of 
  June 
  show 
  a 
  well 
  pronounced 
  defic- 
  

   iency 
  of 
  temperature. 
  

  

  (2). 
  In 
  all 
  cases, 
  of 
  given 
  years, 
  the 
  comparison 
  of 
  the 
  records 
  

   has 
  shown 
  a 
  progressive 
  displacement 
  of 
  the 
  wave 
  of 
  cold. 
  

  

  (3). 
  A 
  characteristic 
  distribution 
  of 
  atmospheric 
  pressure 
  

   over 
  Europe 
  is 
  noticeable. 
  On 
  the 
  ocean 
  a 
  high 
  pressure 
  area, 
  

   extending 
  an 
  anticyclonic 
  tongue 
  eastward, 
  moves 
  slowly 
  from 
  

   the 
  center 
  of 
  action 
  of 
  the 
  Azores 
  northward. 
  

  

  (4). 
  The 
  resultants 
  of 
  the 
  observed 
  wind 
  directions 
  change 
  

   radically. 
  

  

  (5). 
  Considering 
  a 
  long 
  series 
  of 
  observations, 
  groups 
  of 
  years 
  

   may 
  be 
  distinguished 
  for 
  which 
  the 
  temperature 
  depressions 
  

   of 
  May 
  and 
  June 
  are 
  well 
  pronounced, 
  while 
  in 
  other 
  groups 
  

   they 
  occur 
  only 
  occasionally. 
  

  

  ♦Ann. 
  Phys. 
  Chem., 
  clix, 
  36, 
  1876. 
  

  

  f 
  Abh. 
  math. 
  -phys., 
  Kl. 
  K. 
  Bay. 
  Akad. 
  Wiss., 
  xiv, 
  II, 
  69, 
  1883. 
  

  

  {Bull. 
  Soc. 
  Vaud. 
  Sc. 
  (3), 
  xxix, 
  316, 
  1893. 
  

  

  § 
  Abh. 
  K. 
  Preuss. 
  Met. 
  Inst,, 
  ii, 
  No. 
  3, 
  1902. 
  

  

  || 
  Arch. 
  Sc. 
  Phys. 
  et 
  Nat. 
  (4), 
  xxxi, 
  497, 
  1911. 
  

  

  If 
  Meteor. 
  Zeit., 
  xxxi, 
  p. 
  426, 
  1914. 
  

  

  