Weather and Climate Relevance
In well-defined air masses, many (or even most) clouds may have a similar cloud base because this variable is largely controlled by the thermodynamic properties of that air mass, which are relatively homogeneous on a large spatial scale. This is not the case for the cloud tops, which can vary widely from cloud to cloud, as the depth of the cloud is determined by the strength of local convection.
Clouds greatly affect the transfer of radiation in the atmosphere. In the thermal spectral domain, water is a strong absorber (and thus emitter, according to Kirchhoff's law of thermal radiation). Hence clouds exchange thermal radiation between their bases and the underlying planetary surface (land or ocean) by absorbing and re-emitting this infrared radiation at the prevailing temperature: the lower the cloud base, the warmer the cloud particles and the higher the rate of emission. For a synthetic discussion of the impact of clouds (and in particular the role of cloud base) on the climate system, see the IPCC Third Assessment Report, in particular chapter 7.2.
Cloud base is an important meteorological variable for aviation safety, as it determines whether pilots may use Visual Flight Rules (VFR) or must follow Instrument Flight Rules for take-off or landing.
Read more about this topic: Cloud Base
Famous quotes containing the words weather, climate and/or relevance:
“This is the weather the shepherd shuns,
And so do I;
When beeches drip in browns and duns,
And thresh, and ply;”
—Thomas Hardy (1840–1928)
“The climate of Ohio is perfect, considered as the home of an ideal republican people. Climate has much to do with national character.... A climate which permits labor out-of-doors every month in the year and which requires industry to secure comfort—to provide food, shelter, clothing, fuel, etc.—is the very climate which secures the highest civilization.”
—Rutherford Birchard Hayes (1822–1893)
“... whatever men do or know or experience can make sense only to the extent that it can be spoken about. There may be truths beyond speech, and they may be of great relevance to man in the singular, that is, to man in so far as he is not a political being, whatever else he may be. Men in the plural, that is, men in so far as they live and move and act in this world, can experience meaningfulness only because they can talk with and make sense to each other and to themselves.”
—Hannah Arendt (1906–1975)