﻿F. 
  Waldo 
  — 
  Wind 
  Velocities 
  in 
  the 
  United 
  States. 
  439 
  

  

  Dulnth. 
  For 
  these 
  last 
  mentioned 
  places 
  a 
  secondary 
  maxi- 
  

   mum 
  occurs 
  at 
  3 
  h 
  or 
  4 
  h 
  and 
  a 
  second 
  minimum 
  at 
  about 
  6 
  h 
  , 
  

   while 
  for 
  Duluth 
  there 
  is 
  a 
  slight 
  tertiary 
  maximum 
  at 
  22 
  h 
  

   and 
  minimum 
  at 
  20 
  h 
  . 
  For 
  the 
  early 
  hours 
  of 
  the 
  descent 
  

   from 
  the 
  maximum 
  the 
  slope 
  is 
  steeper 
  than 
  in 
  the 
  ascent. 
  

  

  For 
  the 
  Year, 
  the 
  maxima 
  of 
  the 
  curves 
  are 
  nearly 
  as 
  well 
  

   developed 
  as 
  for 
  July, 
  but 
  the 
  amplitude 
  is 
  not 
  quite 
  so 
  great, 
  

   and 
  the 
  period 
  that 
  the 
  maximum 
  is 
  above 
  the 
  nearly 
  level 
  

   minimum 
  period 
  is 
  only 
  about 
  12 
  h 
  , 
  which 
  is 
  less 
  than 
  for 
  July. 
  

   In 
  most 
  cases 
  the 
  minimum 
  occurs 
  at 
  about 
  3 
  h 
  or 
  4 
  h 
  , 
  but 
  the 
  

   whole 
  minimum 
  period 
  is 
  nearly 
  the 
  same, 
  although 
  for 
  Mil- 
  

   waukee 
  it 
  is 
  very 
  irregular, 
  and 
  secondary 
  phases 
  are 
  probably 
  

   present. 
  

  

  Upper 
  Mississippi 
  River 
  Valley 
  Region 
  (Curve 
  14). 
  — 
  For 
  

   January 
  there 
  is 
  a 
  rather 
  sharp-crested 
  narrow 
  maximum 
  rising 
  

   for 
  about 
  9 
  h 
  above 
  a 
  somewhat 
  irregular 
  though 
  level 
  mini- 
  

   mum 
  period, 
  and 
  having 
  a 
  small 
  amplitude. 
  The 
  minimum 
  

   usually 
  occurs 
  at 
  about 
  sunrise, 
  although 
  a 
  near 
  approach 
  to 
  

   the 
  absolute 
  minimum 
  occurs 
  at 
  about 
  sunset 
  or 
  a 
  little 
  later. 
  

   Traces 
  of 
  secondary 
  phenomena 
  are 
  present 
  about 
  three 
  hours 
  

   after 
  midnight 
  for 
  Dubuque, 
  and 
  three 
  hours 
  before 
  midnight 
  

   for 
  Keokuk. 
  At 
  the 
  high 
  exposure 
  of 
  St. 
  Louis 
  there 
  is 
  a 
  

   low 
  flat-crested 
  maximum 
  during 
  the 
  time 
  from 
  9 
  h 
  to 
  15 
  h 
  and 
  

   a 
  secondary 
  sharp-crested 
  maximum 
  of 
  nearly 
  the 
  same 
  ampli- 
  

   tude 
  at 
  midnight 
  ; 
  the 
  principal 
  minimum 
  is 
  at 
  18 
  h 
  and 
  

   secondary 
  at 
  about 
  6 
  h 
  . 
  The 
  extreme 
  amplitude 
  is 
  very 
  slight, 
  

   during 
  the 
  whole 
  month. 
  

  

  For 
  July 
  there 
  is 
  a 
  well 
  developed 
  maximum 
  at 
  from 
  14 
  h 
  

   to 
  16 
  h 
  and 
  in 
  most 
  cases 
  a 
  secondary 
  maximum 
  at 
  about 
  mid- 
  

   night 
  (sometimes 
  a 
  little 
  before, 
  and 
  sometimes 
  a 
  little 
  later). 
  

   The 
  times 
  of 
  minima 
  are 
  variable 
  but 
  usually 
  at 
  6 
  h 
  and 
  21 
  h 
  , 
  or 
  

   a 
  little 
  later 
  ; 
  in 
  some 
  cases 
  the 
  first 
  is 
  the 
  primary 
  and 
  in 
  

   others 
  the 
  secondary. 
  The 
  secondary 
  phases 
  are 
  slight 
  in 
  com- 
  

   parison 
  with 
  the 
  primary. 
  

  

  For 
  the 
  Year, 
  there 
  are 
  well 
  developed 
  maxima 
  at 
  about 
  

   14 
  h 
  and 
  very 
  slight 
  secondary 
  maxima 
  at 
  St. 
  Louis, 
  at 
  or 
  just 
  

   before 
  midnight. 
  The 
  minima 
  occur 
  at 
  or 
  about 
  daybreak, 
  

   with 
  very 
  slight 
  secondary 
  minima 
  at 
  St. 
  Louis 
  at 
  20 
  h 
  . 
  The 
  

   minimum 
  period 
  is 
  quite 
  level. 
  Secondary 
  phases 
  are 
  hardly 
  

   noticeable 
  except 
  at 
  St. 
  Louis. 
  

  

  Great 
  Plains 
  (Curves 
  15 
  and 
  16). 
  — 
  For 
  January 
  in 
  the 
  

   north, 
  the 
  maximum 
  period 
  culminating 
  at 
  13 
  h 
  or 
  14 
  h 
  or 
  15 
  h 
  is 
  

   short 
  (about 
  8 
  h 
  above 
  minimum 
  level), 
  but 
  well 
  marked 
  ; 
  and 
  

   the 
  main 
  minimum 
  is 
  at 
  from 
  5 
  b 
  to 
  8 
  h 
  . 
  Most 
  of 
  the 
  stations 
  

   show 
  secondary 
  maxima, 
  near 
  midnight, 
  and 
  secondary 
  

   minima 
  at 
  about 
  I8 
  h 
  or 
  19 
  h 
  and 
  of 
  nearly 
  equal 
  level 
  with 
  the 
  

   principal 
  minima. 
  In 
  the 
  south 
  the 
  principal 
  maximum 
  

   extends 
  over 
  a 
  longer 
  period 
  and 
  is 
  more 
  flattened 
  at 
  the 
  

  

  