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METEOROLOGY AND CLIMATE
UNIT #7
WHAT YOU NEED TO KNOW FOR THE TEST!
Cloud Formation VocabularyCloud Formation Vocabulary• Absolute humidity – actual amount of water in the air
at that temperature• Condensation nuclei – air particles of dust or salt from
the ocean• Convection – transfer of heat energy by currents• Density – mass per unit volume of a substance• Dew point – temperature at which condensation occurs• Sublimation – change of phase from solid to gas (or gas to solid) with no intermediate liquid phase• Troposphere – lowest layer of the atmosphere where
all weather occurs
Weather instruments measure weather conditions. One of the most important conditions is air pressure, which is measured with a barometer, shown below. See the other commonly used weather instruments:
Rising air pressure =fair weather
Falling air pressure =foul weather
•Thermometer measures temperature. •Anemometer measures wind speed. •Rain gauge measures the amount of rain. •Hygrometer measures humidity. •Wind vane shows wind direction. •Snow gauge measures the amount of snow.
Change of Phases – Heat EnergyESRT pg. 1
If something is getting warmer (increased temperature), heat energy is gained.
If something is getting cooler (decreased temperature), heat energy is released.
HEAT TRANSFERHEAT TRANSFERHow is heat transferred in the atmosphere?
Radiation, Conduction, Convection
HEAT TRANSFER BY CONVECTIONHEAT TRANSFER BY CONVECTIONLocal breezes are generated by unequal heating of
Earth’s surface due to local conditions
Warm, less dense air is pushed upward,while more dense, cool air descends,
creating a SEA BREEZE during the day(sea to land)
Cool, more dense air descends, whilewarm, less dense air is pushed upward,
creating a LAND BREEZE at night(land to sea)
SPECIFIC HEATSPECIFIC HEATThe quantity of heat, measured in joules, needed to raise
the temperature of 1 gram of a substance 1o C.
The higher the specific heat of a substance, the greater amount of heat needed to raise its temperature. If a substance requires more heat to “heat up”, it will take
longer for it to heat up, which means it will also take longer for it to “cool down”.
ESRT pg. 14
Temperature Scale ESRT pg. 14
REMEMBER:The dry bulb is the air temperature.
The wet bulb is swung in the air as water evaporates, removing heat from the bulb
of the thermometer, which causes the temperature to be lower (cooler).
*The closer the air temperature and dewpoint temperature, the higher the
relative humidity (precipitation!).PRACTICE QUESTIONS
ADIABATICISM(OROGRAPHIC EFFECT)
--Dry lapse rate occurs between the land surface and the base of cloud (dew point)—as air ascends, altitude increases/temperature decreases. --Moist lapse rate occurs from dew point to the top of the cloud—as altitude increases/ temperature continues to decrease. --From the mountain peak air descends back down to the land surface—as altitude decreases, temperature increases, and the dry lapse rate continues again down to the base of the mountain at Earth’s surface.
Dry lapse rate: 10o
Moist lapse rate: 6o
STATION MODELS ESRT pg. 13
Higher up in elevation, there is less air above so the air pressure decreases.
At the surface of the Earth the air pressure is greater because there is more air above you!
Altitude and Air Pressure
Density and Air Pressure
Higher weight per volume
The higher the air
density, the
higher theair pressure!
More molecules, packed tightly together
Fewer molecules, spread out.
Lower weight per volume
The lower the air
density, the
lower theair pressure!
Temperature and Air Pressure As air
temperatureincreases,
air pressure decreases!
Cold air is more dense!
Low Pressure!
L
As air temperature decreases, air pressure increases!
Warm air is less dense!High Pressure!
H
The wind blows because air has weight!
1) Cold air weighs
more than warm air, so the pressure
of cold air is
greater.
High Pressure!
H
2) When the sunwarms the air,
it expands,
gets lighter, and rises.
Low Pressure!
L 3) Cooler, heavier air blows to where the
warmer and lighter air was.
CORIOLIS EFFECT
http://www.youtube.com/watch?v=mcPs_OdQOYU
The Coriolis Effect is the apparent curvature of global winds, ocean currents, and everything else that moves freely across the Earth’s surface. The Coriolis Effect is due to the rotation of the Earth on its axis.
If not for the Earth’s rotation, global winds would blow in straight north-south lines. What actually happens is that global winds blow diagonally. The Coriolis Effect influences wind direction around the world in this way: in the Northern Hemisphere it curves winds to the right; in the Southern Hemisphere it curves them left. The exception is with low pressure systems. In these systems there is a balance between the Coriolis Effect, and the pressure gradient force and the winds flow in reverse.
To sum up ‘what is the Coriolis Effect’-- it is an important meteorological force that is used to predict the directional path of storms.
AIR MOVEMENT
Coriolis Effect is the deflection of air near Earth’s surface caused by Earth’s rotation.
N. Hemisphere S. Hemisphere
A wind is named for the direction from which it comes!
Westerly Wind
PRESSURE GRADIENT FORCEPRESSURE GRADIENT FORCEThe change in pressure measured across a given distance is called a “pressure gradient”. The higher the force, the faster the wind speed.
As an air parcel moves from high pressure to low pressure because of the pressure gradient force, it is deflected by the Coriolis force to the right in the Northern Hemisphere.
On which side of the hill is the greatest wind speed, and why?...The wind blows fastest on the left side where the isolines areclosest together. This is where the greatest change is.
Symbol Front
Warm Front -- A warm front is defined as the transition zone where a warm air mass is replacing a cold air mass.
Cold Front -- A cold front is defined as the leading edge of a cooler mass of air, replacing (at ground level) a warmer mass of air.
Stationary Front -- is a boundary between two different air masses, neither of which is strong enough to replace the other.
Weather Fronts - A weather front is a boundary separating two masses of air of different densities.
PRECIPITATIONPRECIPITATION occurs right at the cold front and ahead of the warm front
The COLD air mass front is steep and the WARM air mass front is more gentle.
*NOTE: that the cold, heavier air mass, is associated with HIGH PRESSURE, is typically below the lighter, less dense warm air.
YOU NTK THIS!!!
SYNOPTIC WEATHER MAP
WETWET moisture belt = warm, converging air rising
DRYDRY moisture belt = cool, divergent air sinking
CLIMATE PATTERNSCLIMATE PATTERNS
CLIMATE is the average temperature and amount of precipitation for an area over a long time (annually). Compared to the climate at location A, the climate at location B would most likely be WARMWARM (sinking, compressed air) and DRYDRY (low humidity, away from moisture source)—desert region.
FACTORS INFLUENCING CLIMATE• Latitude
• Altitude
• Mountain ranges
• Oceans/lakes
• Ocean currents
• Landmass location
• Arid air – dry• Humid air – moist
Climate types:• *Arctic – very cold, dry• Polar – cold, moist• Temperate – varied
temperatures (4 seasons)• *Tropical – warm, humid
*(little seasonal change)
