Study sets, textbooks, questions
Upgrade to remove ads
safety exam 3 material
Terms in this set (15)
what does stability class indicate? why is it important?
Pasquill-Gifford stability class ranges from A (most unstable) to F (most stable); D is neutral
Depends on wind speed and quantity of sunlight
Convective Boundary Layer
Unstable to neutral (ABCD)
Stable Boundary Layer
Natural to stable (DEFG)
Difference between unstable, neutral, and stable atmospheric conditions?
unstable- enhance atmospheric turbulence. sun heats ground so air temp near ground is higher then air temp at higher elevations. the air temp difference is unstable because air of lower density is below air of greater density. this influence of buoyancy enhances atmospheric mechanical turbulence.
neutral- when air above the surface warms and the wind speed typically increases, insolation (solar heating) becomes less important. the air temp difference doesn't influence atmospheric mechanical turbulence.
stable- in night time conditions or during the day when ground temp is lower than the air temp at higher elevations, density of air near surface is higher than above the surface. this air temp difference is stable because higher density is below air of lower density. this influence of buoyancy suppresses mechanical atmospheric turbulence.
(higher turbulence = faster mixing)
what time of day can stable atmospheric conditions typically occur?
in night time conditions or during the day when ground temp is lower than the temp at higher elevations, density of air near surface is higher than above the surface.
what is the surface roughness? how is surface roughness related to the mean obstacle height?
surface roughness- irregularities that generate turbulence on the surface
deals with the buildings, trees, and other obstacles
standard practice is to estimate zo based on the surrounding terrain (typically H/z = 6/20 where H is the average roughness element height)
What causes plume meander?
Atmospheric variations in wind direction cause real plumes to change direction or meander. a fixed location may even be inside a plume at some times and outside at others (intermittency). for ground level plumes, a plume meander influences the horizontal extent of a plume much more than the vertical extent
all other things being equal how is the concentration of a passive contaminant at a given location related to the mass release rate?
concentration at a given location is directly proportional to release rate, E.
lower source rates reduce the amount of contaminant moving downwind therefore reducing the concentration at all downwind distances. Cmax = E/(pi
all other things being equal how is the concentration of a passive contaminant at a given location related to the wind speed?
concentration at a given location is inversely proportional to wind speed, u.
higher wind speeds has more turbulent energy available to mix air into cloud. higher wind speeds move contaminant downwind at a faster rate reducing the concentration. Cmax = E/(pi
all other things being equal how is the concentration of a passive contaminant at a given location related to the atmospheric stability?
concentration increases with increased atmospheric stability
how are passive atmospheric dispersion coefficients related to atmospheric stability? for increased atmospheric stability, do dispersion coefficients increase or decrease?
the dispersion coefficients are a function of atmospheric conditions and the distance downwind from the release.
sigma y and sigma z decrease with increased stability.
explain the effect of meander on the concentration of a plume at a given downwind distance
meander decreases the concentration of a plume at a given downwind distance.
explain the effect of meander on the concentration of a puff at a given downwind distance
meander has no effect on a puff
difference between a plume and puff release
plume release is a continuous release while a puff is an instantaneous release.
difference between continuous and instantaneous release
continuous release happens over a long period of time while instantaneous release is a very short release of gas
Sets with similar terms
Earth Systems Geology: Ch. 5
ATMO170A Intro to Weather and Climate
Physics of Climate Change
Other sets by this creator
controls test 4
process exam 3
safety exam new material
safety material exam 4
Other Quizlet sets
Unit 8 Study Guide: Cold War and Decolonization
Accounting Chapter 5
General psychology test 2
exs 216 - exam 4 chapter 17