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 and, weather, climate and/or relevance:
“What
One believes is what matters. Ecstatic identities
Between one’s self and the weather and the things
Of the weather are the belief in one’s element,
The casual reunions, the long-pondered
Surrenders, the repeated sayings that
There is nothing more and that it is enough....”
—Wallace Stevens (1879–1955)
“Family values are a little like family vacations—subject to changeable weather and remembered more fondly with the passage of time. Though it rained all week at the beach, it’s often the momentary rainbows that we remember.”
—Leslie Dreyfous (20th century)
“A positive learning climate in a school for young children is a composite of many things. It is an attitude that respects children. It is a place where children receive guidance and encouragement from the responsible adults around them. It is an environment where children can experiment and try out new ideas without fear of failure. It is an atmosphere that builds children’s self-confidence so they dare to take risks. It is an environment that nurtures a love of learning.”
—Carol B. Hillman (20th century)
“Wherever the relevance of speech is at stake, matters become political by definition, for speech is what makes man a political being.”
—Hannah Arendt (1906–1975)