PHYSICAL OCEANOGRAPHY OF THE GULF OF MAINE 



Difference between surface and air temperatures (° C.) 

 [— signifies that the air was colder, + that it was the warmer] 



671 



It is to be noted that while the air temperature did not fall below that of the 

 water until between 3 and 4 a. m. on the first night, this happened at 9 p. m. on 

 the second. 



In 1920 the air averaged colder than the water in the harbors of Gloucester, 

 Boothbay, and Lubec after about the middle of October. According to the temper- 

 atures collected by Rathbun (1887), the surface was colder than the air at the 

 several lighthouses after the following approximate dates of 1881 to 1883: 



Locality 



Year 



Date 



Pollock Rip 



Thatchers Island 



Boon Island 



Seguin Island 



Matinious Rock 



Mount Desert Bock 

 Petit Manan 



After Nov. 16. 



After Nov. 1. 



After Nov. 8. 



Between Nov. 11 and 16. 



After Oct. 30. 



After Nov. 1. 



After Nov. 6. 



After Nov. 1. 



After Oct. 25. 



Nov. 1 to 6. 



After Oct. 17. 



After Oct. 25. 



Nov. 1 to 6. 



After Nov. 16, but with reversals. 



After Nov. 16. 



After Nov. 6. 



After Nov. 8. 



After Oct. 23. 



After Nov. 26. 



Thus the water in the coastal belt is constantly warmer than the air after the 

 last week of October or the first week in November. From that time on the differ- 

 ence between air and water increases until the middle of January, when the air 

 averages about as much colder than the water as it is warmer in summer (illustrated 

 by the 10-day averages for Gloucester, Boothbay, and Lubec, figs. 29 to 31). Duriug 

 periods of extreme cold, such as come to New England and to the Maritime Prov- 

 inces almost every winter, the spread between air and surface temperatures is even 

 wider than the spread of the reverse order in summer. At Lubec, for example, the 



