+--------------+----+-----+----+-----+----+-----+----+-----+-------+-------+ | WIND | | | | | | | | | | | DIRECTIONS | N. | NE. | E. | SE. | S. | SW. | W. | NW. | | +--------------+----+-----+----+-----+----+-----+----+-----+ + | | | | | | | | | | | + +----+-----+----+-----+----+-----+----+-----+ + | | | | | | | | | | | + +----+-----+----+-----+----+-----+----+-----+ + | TEMPERATURES | | | | | | | | | | + +----+-----+----+-----+----+-----+----+-----+ + | | | | | | | | | | | + +----+-----+----+-----+----+-----+----+-----+ | | | | | | | | | | | | +--------------+----+-----+----+-----+----+-----+----+-----+-------+-------+ | Sums | | | | | | | | | | Total | +--------------+----+-----+----+-----+----+-----+----+-----+-------+-------+ | Cases | | | | | | | | | | Total | +--------------+----+-----+----+-----+----+-----+----+-----+-------+-------+ | Means | | | | | | | | | | Mean | +--------------+----+-----+----+-----+----+-----+----+-----+-------+-------+ Enter the temperature at 8 A.M. on the first day of the month in a column of the table under the proper wind direction. Thus, if the wind is NE., and the temperature 42°, enter 42 in the second column of the table. Repeat the observation for the same station, and for all the other days of the month, recording the temperatures in each case in their appropriate columns in the table. Omit all cases in which the wind is _light_, because winds of low velocities are apt to be considerably affected by local influences. When the observations for the whole month have been entered in the table, add up all the temperatures in each column (_sums_). Find the mean temperature (_means_) observed with each wind direction by dividing the sums by the number of observations in each column (_cases_). Add all the sums together; divide by the total number of cases, and the result will be the mean temperature[5] for the month at the station. The general effect of the different wind directions upon the temperature is shown by a comparison of the means derived from each column with the mean for the month. [Footnote 5: Derived from the 8 A.M. observations. This does not give the true mean temperature.] [Illustration: FIG. 49.]