aeroscopy

from The Century Dictionary.

• noun Divination by means of the air; weather-prophecy.
• noun Examination or observation of the atmosphere; the practice of meteorology.
• noun In zoology, perception or observation of atmospheric conditions, as by insects and snails; the instinctive exercise of aëroscepsy; the operation or result of the faculty of aëroscepsy. See aëroscepsy.

from the GNU version of the Collaborative International Dictionary of English.

• noun The observation of the state and variations of the atmosphere.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun obsolete, meteorology The branch of meteorology that involves the scientific examination of the various properties and composition of the atmosphere, and their variation
• noun rare divination by observation of the sky