Precipitation Flashcards
(131 cards)
1
Q
Atmosphere
A
movement and storage of water is in response to general global circulation and to local vapor pressure gradients
2
Q
Weather
A
constitutes the current conditions of atmosphere (pressure, temp, wind, humidity)
3
Q
Climate
A
summation of weather overtime
4
Q
Pressure
A
result of particles moving about randomly in the atmosphere; force/unit area (lb/in^2 or psi)
5
Q
Pressure at Sea Level
A
14.7 psi or 1013.250 dynes/cm^2 (millibar)
6
Q
Standard Pressure
A
30 inches of Mercury (barometer)
7
Q
Pressure We Feel
A
14.7 lb on every in^2
8
Q
Column of Atmosphere
A
weighs 14.7 lb over 1in^2
9
Q
Water Replacing Mercury
A
33 ft water
10
Q
Pressure and Density
A
decrase with altitude
11
Q
Density
A
changes due to varying mixes of substances and gravity
12
Q
Atmosphere
A
considered as 400 miles deep
13
Q
Jet Stream
A
major transport mechanism for weather patterns and circulation; 500 mb
14
Q
High and Low Pressures
A
exist because the atmosphere is a fluid & can pile up, thin down, speed up, slow down, etc.
15
Q
Winds are Created By
A
gravity which acts on varying density chunks of atmosphere or differences in pressure (high to low)
16
Q
Coriolis Effect
A
an inertial or fictitious force that acts on objects in motion within a frame of reference that rotates; influences movement of atmosphere
17
Q
High Pressure Rotation
A
clockwise
18
Q
Low Pressure Rotation
A
Counter-clockwise
19
Q
Good Weather
A
high pressure systems
20
Q
Bad Weather
A
low pressure systems
21
Q
Significance of Strong Low Pressure
A
associated with stronger winds (stronger pressure difference = stronger wind)
22
Q
Barometer
A
measures pressure; responds to atmospheric pressure
23
Q
Liquid Barometer
A
mercury; glass tube is without protection; has to stay verticle
24
Q
Mechanical Barometer
A
less precise/accurate than mercury
25
Why do we use mercury and not water in barometers?
equivalent is 33 ft of water
26
Temperature
expression of heat, not heat of an object
27
Temperature Changes With
altitude (not at same rate as pressure & density)
28
Temperature Drops
may not be uniform at all
29
Boyle's General Gas Law
p1v1=p2v2
30
Charle's Law
V1/T1=V2/T2
31
Thermometer
measures temperature; min/max
32
Thermometer Issues
don't show records (past data)
33
Humidity
measure of water stored in atmosphere; expression of water vapor and saturation
34
Water Vapor
water in atmosphere in gas form
35
Water Content
extremely variable in space and time
36
Water
3rd most plentiful substance in well mixed homosphere (4%)
37
Nitrogen
1st most plentiful substance in well mixed homosphere (78%)
38
Oxygen
2nd most plentiful substance in well mixed homosphere (21%)
39
Carbon Dioxide
4th most plentiful substance in well mixed homosphere (<1%)
40
Water Content Varies With
latitude, season, and altitude
41
Vapor Pressure
partial pressure of atmosphere due to presense of water droplets; pressure exerted by presence of water; mb or in. of mercury
42
Saturation Vapor Pressure
maximum the atmosphere can hold
43
Warmer Air
holds more water
44
Cooler Air
holds less water
45
As Air Cools
amount of water doesn't necessarily change; ability to hold water reduces
46
Saturation Vapor Pressure is Reached When
temperature drops to the point where the holding capacity of air equals the amount of water in the air
47
Dewpoint
reached when temperature drops to point where actual vapor pressure equals saturation vapor pressure at constant pressure; condensation forms
48
Dewpoint is >32 F
condensate will be water (dew)
49
Dewpoint is <32 F
condensate will be frost
50
Supercooling
temperature gets below dewpoint without condensation forming
51
-40 C or F
spontaneous condensation occurs; dust or ice crystals act as condensation nuclei
52
Fahrenheit (F)
9/5 C + 32
53
Over Ice
vapor pressure is less than over water; ice crystals are good condensation nuclei
54
Relative Humidity
expression of how much water atmosphere is holding compared to what could be held
55
Why does the air in our houses fees so dry in winter?
cold air that seeps into our house has a lower humidity; warm air holds more moisture
56
Why do we feel so warm on humid days?
air is saturated with water, so sweat evaporates slowly
57
Adiabatic
cooling without giving off heat
58
Adiabatic Processes
when air particle is lifted through atmosphere it cools (volume is larger and pressure is less), holds less water, expands, and may not lose heat
59
Clouds
condensed water/ice droplets; not all provide precipitation
60
Ice Clouds
appear more "feathery" than that of water vapor
61
Cloud Basic Scenario
warm air at surface and begins to rise, cools and relative humidity rises until saturation
62
Cloud Types
cirrus, alto, stratus, nimbo, strato, cumulo
63
Cloud Cover
Clear <10%, Scattered 10-50%, Broken 50-90%, Overcast >90%
64
Fog
cloud close to the ground
65
Radiation Fog
back radiation from Earth cools the surface and layer of atmosphere immediately adjacent to earth; cool clear nights
66
Advective Fog
warm moist air transported over cool surface
67
Steam Fog
temperature of lake greater than air above
68
Fog Drip
water droplets from fog adhere to leaves/needles of trees/others
69
Fog Layers
flat/horizontal sections
70
Global Circulation
division at equator; wind moves up and away from equator towards the poles and back again
71
Each Hemisphere
has 3 cells of circulation; rotating up and away from equator towards poles
72
Creating Doldrums/Horse Latitude
at 30 degrees North and South latitude colder air sinks
73
Air at Poles
colder air sinks
74
Creating Polar Front
at 60 degrees North and South latitude, cold and warm air converge
75
Doldrums/Horse Latitude
bored; state or period of inactivity, stagnation, or depression
76
Polar Front
area where cyclonic storms are generated, dry easterlies mix with warm moist westerlies
77
Easterly/Westerly
refer to which direction the wind is coming from
78
Jet Stream
cooler and warmer currents produce front with associated pressure gradient; doesn't cross equator
79
Jet Stream Winds
produced as air flows from high to low pressure; 18,000-30,000 ft
80
Precipitation Generally Caused By
lifting a parcel of air to a zone of lower pressure and corresponding pressure, cooling causes dew point, and creates cloud
81
Cyclonic Storm
large air mass that rotates around a strong center of low atmospheric pressure; cool easterlies brush against warm moist westerlies and motion begins, produced cold and warm fronts, mixing of cold dense air with warm moist air produced precipitation area
82
Summers Here
quick and intense rains, flash floods
83
Fall/Spring Here
drawn out rains and cover larger area
84
Terrain
can cause lifting, which is a major component in precipitation mechanism
85
Mountains
provide lifting for warm advecting moist air; lift, cooling, snow, go off other side warm and dry
86
Lake Effect
have their own ecosystem
87
Convectional Storms
thunderstorms
88
Thunderstorms
warm moist air rapidly lifts (unstable), air cools, precipitation forms, as it falls it cools the air
89
Thunderstorm Updraft
warm moist air lifts up
90
Thunderstorm Downdraft
falling precip cools air; spreads out in all directions at ground, produces gust front
91
Point of Origin
source/feed of warm moist air; appear to "backbuild" here
92
Cold Gust Front
acts as cold front; can feed other storms
93
Why Urban Areas Contribute to Thunderstorms
presence of heat source (pavement reflect heat) and typically darker areas; more flash floods
94
Rainfall
varies in space and time; amounts vary considerably
95
Spatial and Temporal Variability
variance of space and time
96
Raindrop Size
0.4 - 0.7 mm
97
Raindrop Velocity
>20 mph
98
Terminal Velocity of Rain
reached in about 30ft
99
Raindrop Shape
not the traditional dew drop; dome > bowl > splits in 2
100
Terminal Velocity
doesn't speed up anymore
101
Rain Guage
measures rainfall depth
102
Issue with Rain Guages
point coverage and interference (trees, wind, etc.)
103
Radar
radio detection and ranging
104
Standard Guage
non-recording; large: 20in, small: 7in
105
Fisher and Porter Tipping Bucket
most common mechanical guage; records measurements
106
Universal
elite of mechanical guages; vacuum system to reduce wind effect and collect more
107
Radars in Place Right Now
160
108
WSR-88D
Weather Surveillance Radar - 1988 Doppler
109
WSR-88D Purpose
provide coverage for large % of the US
110
WSR-88D Impacts
energy pulses, Z-R Relationship, calibration, assume drop size and distribution, zero-degree isotherm
111
Ice Types
hail, rime, sleet, graupel (large)
112
Ice
result of all lift and picking up moisture, lots of power; difficult to measure, very high reflectivity
113
Snowpack
compressed and hardened by its own weight; reported in depth
114
Snow Water Equivalent (SWE)
ratio of 10:1 and density is 10%
115
Snowfall Most Dense
high water content, high temp
116
Snowfall Least Dense
low water content, low temp
117
Measure Snow and SWE
guages/boards or tubes
118
Why is it difficult to predict snow with radar?
storm's track and intensity can change it drastically
119
Spatial and Temporal Variation Issue
doesn't represent total area coverage,
120
Duration
length of time rain falls
121
Intensity
rate of rain fall or amount/duration
122
Frequency
occurrence/probability; return period
123
Greater the Duration
greater the amount & lower the intensity
124
More Frequent the Storm
shorter the duration & less the intensity
125
100 Year Event
chance of it occurring each year; 1/100th chance of getting that event in 1 year
126
2 Year Event
event will occur on average every 2 years; 50% probability occurring in any given year
127
How to Calculate Areal Average
arithmetic, thiessen, isohyetal, radar grid based
128
Calculate Areal Average: Arthimetic
add all precipitation values and divide (obtain mean)
129
Calculate Areal Average: Thiessen
find area of each gage (connect gages and split into 3 sections from center of gages); weight has more importance and sums to 1 (all gages = 100%); only do it once and just calculate for weight
130
Calculate Areal Average: Isohyetal
find area between lines; better method; do it for each storm
131
Calculate Areal Average: Radar Grid Based
area put onto grid to see concentrated area; need a radar
