l, and the interior land areas as
a rule then have their minimum. The warmer months bring the maximum
rainfall over the continents. Conditions are then favourable for
inflowing damp winds from the adjacent oceans; there is the best
opportunity for convection; thunder-showers readily develop on the hot
afternoons; the capacity of the air for water vapour is greatest. The
marine type of rainfall, with a winter maximum, extends in over the
western borders of the continents, and is also found in the winter
rainfall of the sub-tropical belts. Rainfalls are heaviest along the
tracks of most frequent cyclonic storms.

For continental stations the typical daily march of rainfall shows a
chief maximum in the afternoon, and a secondary maximum in the night or
early morning. The chief minimum comes between 10 A.M. and 2 P.M. Coast
stations generally have a night maximum and a minimum between 10 A.M.
and 4 P.M.

_Humidity and Cloudiness._--S.A. Arrhenius gives the mean cloudiness for
different latitudes as follows:--

+-----------+----+
| 70 deg. N.| 59 |
| 60 deg. | 61 |
| 50 deg. | 48 |
| 40 deg. | 49 |
| 30 deg. | 42 |
| 20 deg. | 40 |
| 10 deg. | 50 |
| Eq. | 58 |
| 10 deg. | 57 |
| 20 deg. | 48 |
| 30 deg. | 46 |
| 40 deg. | 56 |
| 50 deg. | 66 |
| 60 deg. S.| 75 |
+-----------+----+

The higher latitudes of the temperate zones thus have a mean cloudiness
which equals and even exceeds that of the equatorial belt. The amounts
are greater over the oceans and coasts than inland. The belts of minimum
cloudiness are at about lat. 30 deg. N. and S. Over the continental
interiors the cloudiest season is summer, but the amount is never very
large. Otherwise, winter is generally the cloudiest season and with a
fairly high mean annual amount.

The absolute humidity as a whole decreases as the temperature falls. The
relative humidity averages 90%, more or less, over the oceans, and is
high under the clouds and rain of cyclonic storms, but depends, on land,
upon the wind direction, winds from an ocean or from a lower latitude
being damper, and those from a continent or from a colder latitude being
drier.

_Seasons._--Seasons in the temperate zones are classified according to
temperature; not, as in the tropics, by rainfall. The four seasons are
important characteristics, especially of the middle latitudes of the
north temperate zone. Towards the