﻿F 
  Waldo 
  — 
  Wind 
  Velocities 
  in 
  the 
  United 
  States. 
  437 
  

  

  absolute 
  changes 
  ; 
  usually 
  the 
  max. 
  occurs 
  at 
  14 
  h 
  to 
  16 
  h 
  . 
  The 
  

   irregularity 
  is 
  greatest 
  along 
  the 
  Mississippi 
  River, 
  at 
  Vicks- 
  

   burg 
  and 
  Memphis, 
  where 
  the 
  maximum 
  is 
  so 
  slightly 
  devel- 
  

   oped 
  that 
  the 
  secondary 
  maximum 
  is 
  nearly 
  or 
  quite 
  as 
  great 
  as 
  

   the 
  primary 
  ; 
  this 
  is 
  not 
  due 
  to 
  the 
  greater 
  development 
  of 
  the 
  

   secondary 
  but 
  the 
  lack 
  of 
  development 
  of 
  the 
  primary. 
  For 
  

   Yicksburg, 
  the 
  minimum 
  has 
  about 
  the 
  same 
  absolute 
  value 
  in 
  

   both 
  phases, 
  but 
  for 
  Memphis 
  the 
  afternoon 
  minimum 
  (at 
  

   about 
  19 
  h 
  ) 
  is 
  slightly 
  the 
  lower 
  of 
  the 
  two. 
  On 
  the 
  lower 
  

   Arkansas 
  River, 
  with 
  a 
  more 
  east-westerly 
  river 
  exposure, 
  the 
  

   primary 
  maximum 
  at 
  13 
  h 
  or 
  14 
  h 
  is 
  well 
  developed, 
  but 
  the 
  

   secondary 
  phases 
  are 
  hardly 
  perceptible, 
  and 
  the 
  principal 
  

   minimum 
  is 
  hardly 
  to 
  be 
  distinguished 
  since 
  it 
  is 
  but 
  little 
  

   below 
  the 
  long, 
  nearly 
  level, 
  period 
  of 
  minimum 
  wind. 
  

  

  For 
  July, 
  there 
  appears 
  to 
  be 
  but 
  a 
  single 
  well 
  defined 
  maxi- 
  

   mum 
  culminating 
  about 
  the 
  middle 
  of 
  the 
  afternoon, 
  at 
  about 
  

   16 
  h 
  , 
  and 
  a 
  minimum 
  is 
  reached 
  just 
  before 
  or 
  about 
  midnight. 
  

   The 
  slight 
  traces 
  of 
  secondary 
  phenomena 
  can 
  hardly 
  be 
  

   ascribed 
  to 
  other 
  than 
  accidental 
  errors 
  of 
  exposure, 
  etc. 
  

  

  The 
  curves 
  for 
  the 
  Year 
  are 
  very 
  similar 
  to 
  those 
  for 
  July, 
  but 
  

   the 
  amplitudes 
  are 
  not 
  quite 
  so 
  great, 
  and 
  the 
  minimum 
  period 
  

   is 
  more 
  nearly 
  a 
  uniform 
  level. 
  In 
  all 
  cases 
  the 
  descent 
  from 
  the 
  

   culminating 
  maximum 
  is 
  steeper 
  than 
  the 
  ascent 
  to 
  it. 
  The 
  

   absolute 
  maximum 
  is 
  at 
  about 
  15 
  h 
  and 
  the 
  minimum 
  at 
  or 
  just 
  

   before 
  midnight. 
  

  

  Ohio 
  River 
  Region 
  (Curve 
  13). 
  — 
  For 
  January 
  the 
  maxi- 
  

   mum, 
  at 
  about 
  14 
  h 
  , 
  is 
  well 
  defined 
  and 
  with 
  a 
  rounded 
  crest 
  in 
  

   some 
  cases, 
  and 
  in 
  others 
  a 
  pointed 
  crest, 
  but 
  the 
  slopes 
  on 
  

   either 
  side 
  are 
  symmetrical. 
  There 
  is 
  just 
  a 
  trace 
  of 
  a 
  second- 
  

   ary 
  maximum 
  at 
  some 
  of 
  the 
  stations, 
  which 
  becomes 
  best 
  

   defined 
  at 
  Knoxville 
  ; 
  while 
  the 
  minimum 
  occurs 
  for 
  some 
  of 
  

   the 
  stations 
  before 
  midnight, 
  and 
  for 
  others 
  after 
  midnight, 
  so 
  

   that 
  the 
  usual 
  times 
  of 
  both 
  primary 
  and 
  secondary 
  minima 
  are 
  

   represented 
  in 
  speaking 
  of 
  the 
  principal 
  minimum, 
  and 
  at 
  

   Knoxville 
  minima 
  of 
  about 
  equal 
  magnitudes 
  occur 
  for 
  both 
  

   primary 
  and 
  secondary 
  phases. 
  

  

  For 
  July 
  the 
  maxima 
  are 
  well 
  developed, 
  and 
  usually 
  with 
  

   rounded, 
  rather 
  symmetrical 
  crests 
  ; 
  and 
  the 
  period 
  of 
  excess 
  

   above 
  the 
  somewhat 
  level 
  period 
  of 
  deficiency 
  is 
  about 
  four- 
  

   teen 
  or 
  fifteen 
  hours. 
  The 
  time 
  of 
  extreme 
  maximum 
  covers 
  

   most 
  of 
  the 
  afternoon 
  hours, 
  extending 
  from 
  13 
  h 
  or 
  14 
  h 
  to 
  17 
  h 
  

   or 
  18 
  h 
  . 
  There 
  is 
  but 
  little 
  more 
  than 
  a 
  suspicion 
  of 
  a 
  secondary 
  

   maximum 
  phase 
  at 
  about 
  midnight, 
  and 
  although 
  it 
  can 
  be 
  

   noticed 
  in 
  some 
  cases, 
  yet 
  it 
  is 
  entirely 
  wanting 
  in 
  others. 
  

   The 
  minimum 
  occurs 
  a 
  little 
  before 
  sunrise, 
  and 
  consequently 
  

   just 
  precedes 
  the 
  beginning 
  of 
  the 
  ascent 
  to 
  the 
  principal 
  

   maximum. 
  

  

  