=Types of Change of Temperature with Altitude.=--When the records of temperature and humidity made aloft by the kite-meteorograph and at the stations near the ground are plotted in relation to altitude, they are found to be easily divisible into a few types. In Plate X., Type 1 represents the decrease of temperature on most fair days from the ground to altitudes of a mile or more, when no clouds are met. The continuous line, plotted from the records of the ascent, represents the day conditions, and the broken line, plotted from the records of the descent, represents the night conditions. This curve shows that with increasing altitude the temperature falls uniformly during the day and approximately at the adiabatic rate represented by the dotted lines. The fall of temperature with increasing altitude during the night is slower than during the day, and in fact, from the earth's surface to an altitude of a few hundred metres, there is often a rise of temperature with height, so that the air at altitudes of from 300 to 500 metres may be considerably warmer than it is at the ground. This was shown in the descent on October 8, 1896, and is found in Type 3. [Illustration: PLATE X.--CHANGES WITH HEIGHT RECORDED BY KITES AT BLUE HILL.] When clouds are traversed during the flight, the temperature curve assumes the form of Type 2. The continuous curve is plotted from the records of an ascent; the broken curve from the records of the descent, both occurring in the day-time. The temperature falls at the adiabatic rate in unsaturated air till the base of the cumulus cloud is reached. It falls at a slower rate in the cloud, the rate probably being that computed by physicists as the adiabatic rate for air in which condensation is taking place. Above the clouds, the fall of temperature appears to be very slow. Type 3 is a condition which persists throughout the day and night, and it resembles the night form of Type 1. The temperature rises very rapidly for a short distance above the ground and then falls, with increase of height, somewhat slower than the adiabatic rate. The rise of temperature near the ground with increasing height is more marked after sunset than during the day-time.