From  an  oceanographical  point  of  view  the
areas  having  a  large  range  of  surface  tempera-
ture are  extremely  important  iii  their  effect
on  organisms,  and  they  will  be  further  referred
to  in  later  chapters.
The  lowest  recorded  temperature  at  the
surface  of  the  sea  is  26°  F.  observed  in  the


^6  THE    OCEAN

North  Atlantic  eastward  of  Nova  Scotia,  and
the  highest  reading  in  the  open  ocean  is  90°  F.
recorded  in  the  tropical  Pacific  both  north
and  south  of  the  equator,  while  readings  of
94°  and  96°  F.  have  been  recorded  in  the
Red  Sea  and  Persian  Gulf  respectively.  The
greatest  known  range  of  temperature  in  the
surface  waters  throughout  the  whole  world  is
thus  70°  F.  (from  26°  to  96°),  being  very  small
when  compared  with  the  extreme  variation  of
the  temperature  over  the  land-surfaces  of  the
globe,  which  may  exceed  220°  F.
Temperature  Conditions  beneath  the  Surface,
— ^Let  us  now  turn  to  the  distribution  of  tem-
perature in  the  depths  of  the  ocean.  Except
in  the  icy  regions  of  the  far  north  and  far
south,  and  in  some  other  exceptional  positions,
the  temperature  of  ocean  water  decreases
from  the  surface  downwards  to  the  bottom.
