﻿THE 
  

  

  AMERICAN 
  JOURNAL 
  OF 
  SCIENCE 
  

  

  [FOURTH 
  SERIES. 
  ] 
  

  

  Aet. 
  XL. 
  — 
  Types 
  of 
  March 
  Weather 
  in 
  the 
  United 
  States. 
  

   The 
  relations 
  existing 
  heticeen 
  mean 
  atmospheric 
  pressure, 
  

   the 
  prevailing 
  character 
  of 
  the 
  weather, 
  and 
  the 
  paths 
  of 
  

   storms; 
  by 
  Oliver 
  Lanard 
  Fassig. 
  With 
  Plates 
  YI 
  

   andYJI. 
  

  

  Introduction. 
  — 
  It 
  has 
  long 
  been 
  recognized 
  that 
  the 
  field 
  of 
  

   view 
  of 
  a 
  national 
  weather 
  service 
  is 
  too 
  small 
  to 
  study 
  to 
  

   the 
  best 
  advantage 
  the 
  daily 
  weather 
  phenomena 
  as 
  they 
  pass 
  

   over 
  any 
  one 
  country. 
  

  

  In 
  the 
  past 
  twenty 
  years, 
  several 
  researches 
  of 
  great 
  import- 
  

   ance 
  have 
  appeared 
  in 
  which 
  the 
  field 
  of 
  investigation 
  com- 
  

   prised 
  large 
  portions 
  of 
  the 
  northern 
  hemisphere, 
  some 
  of 
  them 
  

   indeed 
  including 
  both 
  hemispheres. 
  The 
  results 
  of 
  these 
  

   investigations 
  show 
  that 
  the 
  weather 
  of 
  a 
  certain 
  locality 
  is 
  

   intimately 
  associated 
  with 
  atmospheric 
  conditions 
  very 
  far 
  

   removed 
  from 
  the 
  immediate 
  locality 
  under 
  consideration. 
  

   For 
  example, 
  Hofimeyer 
  and 
  Teisserenc 
  de 
  Bort 
  have 
  shown 
  

   that 
  certain 
  conditions 
  of 
  pressure 
  over 
  the 
  Xorth 
  xAtlantic 
  

   Ocean 
  have 
  a 
  direct 
  bearing 
  upon 
  the 
  weather 
  of 
  Central 
  

   Europe. 
  Blandford 
  and 
  Eliot 
  have 
  demonstrated 
  that 
  certain 
  

   marked 
  phases 
  of 
  Indian 
  weather 
  find 
  their 
  explanation 
  in 
  

   pressure 
  conditions 
  in 
  Central 
  Asia 
  and 
  over 
  the 
  Indian 
  Ocean. 
  , 
  

   There 
  are 
  a 
  few 
  well-defined 
  and 
  persistent 
  areas 
  of 
  high 
  and 
  

   low 
  pressure 
  of 
  great 
  extent 
  in 
  both 
  hemispheres 
  which 
  con- 
  

   trol 
  very 
  largely 
  the 
  weather 
  conditions 
  of 
  the 
  globe. 
  Recent 
  

   researches 
  tend 
  to 
  show 
  that 
  some 
  of 
  the 
  attention 
  heretofore 
  

   given 
  to 
  transient 
  cyclonic 
  areas 
  might 
  well 
  be 
  diverted 
  to 
  the 
  

   study 
  of 
  the 
  so-called 
  ^permanent 
  high 
  areas. 
  The 
  extensive 
  

   areas 
  of 
  high 
  pressure 
  found 
  upon 
  any 
  chart 
  showing 
  the 
  mean 
  

   monthly 
  pressure 
  conditions 
  over 
  the 
  globe 
  are 
  real 
  forces 
  in 
  

  

  Am. 
  Jouk. 
  Sci.— 
  Fourth 
  Series, 
  Yol. 
  YIII, 
  No. 
  47.— 
  November, 
  1899. 
  

   22 
  

  

  