Chapter 5. Cloud Development and Precipitation. Equlibrium. Atmospheric Stability. Air is in stable equilibrium when after being lifted or lowered, it tends to return to its original position – resists upward and downward air motions. Air Parcel- balloon like blob of air
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Cloud Development and Precipitation
Dry air example
Saturated air example
that inhibits vertical air motions and allows fog and haze to linger
close to the ground.
Unstable Air atmosphere
Dry air example
Unstable air. The forest fire heats the air, causing instability near the surface. Warm, less-dense air (and smoke) bubbles upward, expanding and cooling as it rises.
Conditionally unstable air. instability near the surface. Warm, less-dense air (and smoke) bubbles upward, expanding and cooling as it rises.The atmosphere is stable if the rising air is unsaturated...
(See text figure 5.7 on page 116)
When the environmental lapse rate is greater than the dry adiabatic rate, the atmosphere is absolutely unstable. When the environmental lapse rate is less than the moist adiabatic rate, the atmosphere is absolutely stable. And when the environmental lapse rate lies between the dry adiabatic rate and the moist adiabatic rate (shaded green area), the atmosphere is conditionally unstable
Cumulus clouds developing into thunderstorms in a conditionally unstable
atmosphere over the Great Plains. (Note the anvil in the distance)
Thermals forming cumulus clouds conditionally unstable
Lenticular clouds (mountain wave clouds) over Mount Shasta in Northern California
(heaviest precipitation occurs in those clouds with most vertical development)
Supercooled water nuclei
Collison coalescence occurs here
The distribution of ice and water in a cumulonimbus cloud.
Natural seeding by cirrus clouds may form bands of precipitation downwind of a mountain chain.
Virga precipitation downwind of a mountain chain.
Fallstreaks precipitation downwind of a mountain chain.
Dendrite snowflakes – most common form of snow. precipitation downwind of a mountain chain.
Sleet forms when a partially melted snowflake or a cold raindrop freezes into a pellet of ice before reaching the ground.
Rime -An accumulation of rime forms on tree branches as supercooled fog droplets freeze on contact in the below-freezing air.
A heavy coating of freezing rain during this ice storm caused tree limbs to break and power lines to sag.
Vertical temperature profiles (solid red line) associated with freezing rain.
The accumulation of small hail after a thunderstorm. The hail formed as supercooled cloud droplets collected on ice particles called graupel inside a cumulonimbus cloud.
The giant Coffeyville hailstone first cut then photographed under regular light...
September 1970 weighed 1.67 lbs.
Doppler radar display showing precipitation intensity over Oklahoma for April 24, 1999. The numbers under the letters DBZ represent the logarithmic scale for measuring the size and volume of precipitation particles
Doppler radar display showing 1-hour rainfall amounts over Oklahoma for April 24, 1999.