24 Questions
What is the primary reason for the absence of clouds on a warm and sunny day?
High atmospheric pressure
Who is credited with proposing a system for classifying clouds?
Luke Howard
What is the term for the particles that facilitate cloud formation?
Condensation nuclei
How are clouds classified in terms of their height?
By their height above mean sea level
What is the Latin name for 'rain bearer' clouds?
Nimbus
What prefix is used to denote 'medium' level clouds?
Alto
What natural phenomenon led to an increase in condensation nuclei in the late 18th century?
Volcanic eruptions
What is the term for the process by which air warms up as it sinks into the lower atmosphere?
Compression
What is the primary mechanism by which clouds form in the atmosphere?
Condensation of water vapor by cooling the air to the point of saturation
What is the term used to describe the lifting of air caused by mountains or higher terrain?
Orographic lifting
What is the name given to the process by which air is forced up a slope or valley by daytime heating?
Thermal lifting
What is the term used to describe the cooling of air at a rate of 5.5°F per 1000 feet?
Dry adiabatic lapse rate
What is the primary factor that influences the formation and appearance of a cloud?
Stability of the atmosphere
What is the term used to describe a visible collection of billions of minute water and/or ice particles suspended in the atmosphere?
Cloud
What happens to the air when it is forced up a slope or valley by daytime heating?
It cools at the dry adiabatic lapse rate
What is the name given to the process by which clouds form under stable and unstable atmospheric conditions?
Cloud formation
What factor is necessary for condensation to take place in the formation of clouds?
The presence of condensation nuclei
Why do clouds appear white?
Because of the scattering of light by water droplets
What is the primary reason that clouds stop growing upwards?
The end of the release of latent heat
What is the term for the heat released or absorbed during a phase change?
Latent heat
What is the name of the layer of the atmosphere where temperatures rise with altitude?
Stratosphere
What is the term for the small particles in the air that enable condensation to take place?
Condensation nuclei
What is the reason for the yellowish or brownish tinge of some clouds?
Air pollution
What is the reason why there are no clouds on some days?
The lack of turbulent eddies in the air
Study Notes
Clouds and Atmospheric Conditions
- On warm and sunny days with clear blue skies, there are no clouds due to high pressure or anticyclones, causing air to sink slowly, warm up, and prevent condensation.
- Lack of clouds is caused by the type of pressure, which prevents cloud formation mechanisms.
Cloud Classification
- Luke Howard, a British chemist and meteorologist, proposed a system of cloud classification in 1803, which is now the basis of the international classification.
- Howard recognized four main types of clouds: Cumulus (heaped or in a pile), Stratus (in a sheet or layer), Cirrus (thread-like, hairy, or curled), and Nimbus (a rain bearer).
- The Latin words 'altum' (height) and the four cloud types are used to derive the names of the ten main cloud types, based on their appearance and height above sea level.
Cloud Formation
- Clouds form through condensation by cooling the air to the point of saturation, either within a rising column of air or by some other cooling mechanism.
- Cloud formation is influenced by the stability of the atmosphere and can occur under both stable and unstable conditions.
- Four atmospheric lifting processes contribute to cloud formation: orographic lift, thermal lift, frontal lift, and upper-level lift associated with the jet stream.
Orographic Lift
- Orographic lift occurs when an air mass is forced up a slope or valley by daytime heating or by colliding with a mountain barrier.
- Air is cooled at the dry adiabatic lapse rate (5.5°F per 1000 feet) as it rises.
Condensation and Cloud Formation
- Water vapor needs something to condense onto, such as condensation nuclei (salt, dust, and smoke particles) in the air.
- Condensation nuclei enable condensation to take place when the air is saturated.
Cloud Color and Appearance
- The color of clouds is influenced by the scattering of sunlight by water droplets in the cloud, which scatters all colors of the spectrum equally.
- Clouds may appear yellowish or brownish due to air pollution.
Cloud Growth Limitation
- The release of latent heat during condensation allows a parcel of air to rise until all surplus water vapor has condensed and latent heat is released.
- The end of the release of latent heat through condensation is the main reason that stops clouds from growing upwards.
- Other factors limiting cloud growth include strong upper atmospheric winds and temperature changes at high altitudes.
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