energy
the property of a system that enables it to do work
Temperature
Refers to the “hotness” and “coldness” of an object or a substance
Heat
form of energy transferred between objects by virtue of temperature differences
Heat Capacity
Ratio of Heat absorbed, or released, by a system compared to the corresponding temperature rise/fall
Latent Heat
Heat energy required for change of state
Latent heat is absorbed up during:
1) Melting Ice
2) Evaporation/vaporization
3) Sublimation
Latent heat is released down during:
1) Condensation
2) Deposition
3) Freezing
thermometers
expansion and contraction of liquid on an indexed scale
Maximum thermometers contain:
Mercury
Minimum thermometers contain:
Alcohol
Hygrothemometers
Used in airports
Radiometer
Satellite
- remotely measure cloud top temperatures
Bimetallic thermometer
thermograph application
Guidelines for proper thermometer placement:
1) no direct sunlight
2) well ventilated
3) shielded from radiating surfaces
4) 5 ft. above the ground
5) above grassy/vegetated area
6) the more natural the better
Fahrenheit scale
used only in US
• Freezing point: 32 F
• Boiling Point: 212 F
• Body Heat: 98.6 F
Fahrenheit boiling point
212 F
Fahrenheit freezing point
32 F
Fahrenheit body heat
98.6 F
Celsius Scale
A degree of celsius is larger than a degree of Fahrenheit by a factor of 1.8
Celsius Boiling Point
100 C
Celsius Freezing point
0 C
Kelvin Scale
No negative numbers
- 0 means molecular motion has ceased
Kelvin boiling Point
373 K
Kelvin Freezing Point
273 K
Temperature Conversion (F to C)
F - 32 divided by 1.8
Temperature Conversion (C to F)
C * 1.8 + 32
Means that control temperature
solar radiation is primary control
- -location to location differences
1) differential heating of land/water
2) ocean currents
3) elevation
4) altitude and geographic location
When is temperature recoded?
Temperature is recoded every hour at thousands of locations
- mainly used for aviation purposes
HDD definition:
Heating Degree Days
CDD definition:
Cooling Degree Days
HDD/CDD are:
A practical method of evaluation energy demands and consumption
-cumulative (annually)
HDD Season
July through june
CDD Season
January though december
Heat Stress Index two main factors
1) temperature
2) humidity
Wind Chill Index two main factors
1) air temperature
2) wind speed
Water Vapor
Most important element in the atmosphere when considering weather and climate
-highly variable from 0% to 4%
Hydrologic Cycle
1) evaporation
2) condensation
3) transpiration
4) Infiltration
Humidity definition
different ways of specifying the amount of water vapor in the air
Absolute humidity
the weight of the water vapor per volume of air (parcel)
Specific humidity
comparing weight of the water vapor per volume of air (parcel) with the total weight if the air in the parcel including the water vapor
Mixing Ratio
comparing the weight of the water vapor per volume of air (parcel) with the weight of the remaining dry air
Parcel
A specified volume of air
Relative humidity ***
ratio of the airs actual water vapor content compared with the amount of water vapor required for saturation at a given temperature
Dew point temperature **
the temperature to which a parcel of air would need to be cooled to in order for the given parcel of air to reach saturation
-tells amount of moisture in the air
Tells the amount of moisture in the air
Dew Point Temperature
How is Humidity Measured?
Devices including
1) dew cell
2) chilled mirror technology
3) Sling psychrometer
4) electronic hygrometers
5) infrared hygrometers
6) hair hygrometer
dew Cell
directly measures the air’s actual water vapor pressure
chilled mirror technology
cooling a mirrored surface and putting it in contact with a sample gas (air) until condensation occurs
Atmospheric Stability
refers to a state of equilibrium of th atmosphere
How atmospheric stability is determined:
look at the temperature of a parcel of air as it rises and/or sinks in the atmosphere and compare that temperature to the temperature of the surrounding environment (air outside the sample parcel)
Adiabatic Process
when a given parcel of air expands/cools or compresses/ warms with NO interchange of heat with its outside environment
diabetic Process
when a given parcel of air expand/ cools or contracts/warms with interchange of heat with its outside environment
As air parcels rise or shrink in the atmosphere:
we assume adiabatic cooling/heating process
Stable air:
resists change
unstable air
once forced upwards initially, air rises
atmospheric stablity is increased by
1) radiational cooling of the earths surface after sunset
2) cooling of air mass from below as it moves over a colder surface
3) subsidence of an air column
Atmospheric instablity is enhanced by:
1) intense solar heating
2) heating of air mass from below as moves over a warmer surface
3) forceful lifting of air
Dew
water that has condensed onto objects near the ground when the temperature of those objects has cooled below the dew point temperature of the surrounding areas
frost
a covering of ice crystals produced by deposition on exposed surfaces when the air temperature falls below the freezing point and the temperature of the exposed object falls below the surrounding air’s dew point temperature
cloud formation
most clouds form as air rises, expands, and cools
cloud formation process
1) surface heating and free convection
2) topographic lift
3) widespread lifting (assent) due to surface convergence
4) uplift along weather fronts
fog
a cloud with its base at the earths surface
Stratus (Latin Root)
Layer
Cumulus (Latin Root)
Heap
Nimbus (Latin Root)
Violent rain
Cirrus
Curl of hair
Cirrus (Ci)
-High Cloud
thin, whispy clouds blown by high winds aloft into long streamers
Cirrocumulis (Cc)
-High Cloud
small rounded white puffs that can occur individually or in long rows
Altocumulus
-Middle Clouds
gray, puffy masses sometimes rolled out in parallel waves or bands
Sign of mid-level instability
Altostratus (As)
-Middle Cloud
Gray to Gray-Blue (never white) clouds layer that often covers the entire sky
No shadow case at the ground
Stratus (St)
-Low Clouds
uniform grayish cloud that can cover parts or the entire sky
If on ground, known as fog
Stratocumulus (Sc)
-Low Clouds
low, lumpy cloud layer that can appear in rows, patches, or round masses with blue sky noted between individual cloud elements
Nimbostratus
-Low Clouds
Dark Gray “wet looking” cloud layer associated with light to moderate continuously falling precipitation
-Not characterized by thunder and lightning
Cumulus (Cu)
-clouds of Vertical extent
in the form of an individual, detached dome or tower
-usually very dense and defined
Cumulus fractus:
- Clouds of vertical extent
cumulus clouds that appear small and broken in fragments
Cumulous Congestus
- Clouds of vertical extent
Moderate congestus
Towering Congestus
Building Congestus
Cumuloninbus (Cb)
- clouds of vertical extent
a precipitating thunderstorm cloud that produces heavy rain as well as lightning and thunder
Lenticularis (Cloud Subtype)
Lens like
Fractus (Cloud Subtype)
broken or fractured
Humilis (Cloud Subtype)
of small size
congestus (Cloud Subtype)
to pile up; become congested
undulates (Cloud Subtype)
having waves
translucidus (Cloud Subtype)
to shine through
mammatus (Cloud Subtype)
bag/pouch like; mammory
Pileus (Cloud Subtype)
cap
castellanus (Cloud Subtype)
small castles
contalis (Cloud Subtype)
condensation trail
Drizzle
very small, numerous, and uniformly dispersed water drops that appear to float
Rain
precipitation in the form of liquid drops
Freezing Rain
falls in liquid form but freezes upon impact to form a coating of glaze on the ground and exposed objects
freezing drizzle
falls in small liquid form but freezes upon impact to form a coating of glaze on the ground and exposed objects
Ice pellets/ sleet
a type of cold weather precipitation consisting of transparent or translucent pellets of ice
Snow
Cold weather precipitation form composed of white or translucent ice crystals