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“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”
Aviation WeatherAviation WeatherAviation WeatherAviation WeatherDynamically SpeakingDynamically Speaking
Written for the Notre Dame Pilot Initiative By the Pilots of the University of Notre Dame
Written for the Notre Dame Pilot Initiative By the Pilots of the University of Notre Dame
QuoteQuoteQuoteQuote
Just remember, if you crash because of weather, your funeral will be held on a sunny day. –Layton A. Bennett
Just remember, if you crash because of weather, your funeral will be held on a sunny day. –Layton A. Bennett
Lesson PlanLesson PlanLesson PlanLesson PlanWill learn
Atmosphere & Global Circulation Weather & Climate Clouds & Stability Weather Forecasting
Will be able to recite Air Mass Types Lapse Rates Stages of Thunderstorm Development Types of Fog & Clouds
Will be able to distinguish Pictures of different cloud types
Will learn Atmosphere & Global Circulation Weather & Climate Clouds & Stability Weather Forecasting
Will be able to recite Air Mass Types Lapse Rates Stages of Thunderstorm Development Types of Fog & Clouds
Will be able to distinguish Pictures of different cloud types
“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”
The AtmosphereThe Atmosphere&&
Global CirculationGlobal Circulation
The AtmosphereThe Atmosphere&&
Global CirculationGlobal Circulation
Atmospheric CompositionAtmospheric CompositionAtmospheric CompositionAtmospheric Composition
Earth's atmosphere has a unique composition of gases when compared to that of the other planets in the solar system.
Earth's atmosphere has a unique composition of gases when compared to that of the other planets in the solar system.
Nitrogen78%
Oxygen21%
Argon1% Other
0%
At greater altitudes, the same volume of air contains fewer molecules of the gases that make it up. This means that the density of air decreases with increasing altitude.
At greater altitudes, the same volume of air contains fewer molecules of the gases that make it up. This means that the density of air decreases with increasing altitude.
The earth's atmosphere thins rapidly with increasing altitude and is much closer to the earth than most people realize.
The earth's atmosphere thins rapidly with increasing altitude and is much closer to the earth than most people realize.
Thermal Model of the AtmosphereThermal Model of the AtmosphereThermal Model of the AtmosphereThermal Model of the Atmosphere
Sunlight AngleSunlight AngleSunlight AngleSunlight Angle
On a global, yearly basis, the equatorial region of the earth receives more direct incoming solar radiation than the higher latitudes. As a result, average temperatures are higher in the equatorial region and decrease with latitude toward both poles. This sets the stage for worldwide patterns of prevailing winds, high and low areas of atmospheric pressure, and climatic patterns.
On a global, yearly basis, the equatorial region of the earth receives more direct incoming solar radiation than the higher latitudes. As a result, average temperatures are higher in the equatorial region and decrease with latitude toward both poles. This sets the stage for worldwide patterns of prevailing winds, high and low areas of atmospheric pressure, and climatic patterns.
Global Wind PatternsGlobal Wind PatternsGlobal Wind PatternsGlobal Wind Patterns
Hot air rises over the equator due to the fact that it is less dense.
This is called the intertropical convergence zone
This rising air cools as it rises resulting in precipitation in the region of the ITCZ.
The air then travels north and south at high altitude.
Hot air rises over the equator due to the fact that it is less dense.
This is called the intertropical convergence zone
This rising air cools as it rises resulting in precipitation in the region of the ITCZ.
The air then travels north and south at high altitude.
Global CirculationGlobal CirculationGlobal CirculationGlobal Circulation
With Globe, Coriolis Seasons – Have kid
stand on table as sun Chris Columbus -
trades With Fan,
demonstrate orthographic lifting
With Globe, Coriolis Seasons – Have kid
stand on table as sun Chris Columbus -
trades With Fan,
demonstrate orthographic lifting
Global Wind PatternsGlobal Wind PatternsGlobal Wind PatternsGlobal Wind Patterns
Hot air rises over the equator due to the fact that it is less dense.
The cooled air descends to reach the surface at about 24 ON and 24 OS of the equator.This forms a high pressure areaThe great deserts of the world are
located in this high pressure area
Hot air rises over the equator due to the fact that it is less dense.
The cooled air descends to reach the surface at about 24 ON and 24 OS of the equator.This forms a high pressure areaThe great deserts of the world are
located in this high pressure area
Coriolis EffectCoriolis EffectCoriolis EffectCoriolis Effect
An object in motion in the northern hemisphere appears to turn to the right.
An object in motion in the northern hemisphere appears to turn to the right.
An object in motion in the southern hemisphere appears to turn to the left.
An object in motion in the southern hemisphere appears to turn to the left.
Global Circ PixGlobal Circ PixGlobal Circ PixGlobal Circ Pix
Part of the generalized global circulation pattern of the earth's atmosphere. The scale of upward movement of air above the intertropical convergence zone is exaggerated for clarity. The troposphere over the equator is thicker than elsewhere, reaching a height of about 12 mi.
Part of the generalized global circulation pattern of the earth's atmosphere. The scale of upward movement of air above the intertropical convergence zone is exaggerated for clarity. The troposphere over the equator is thicker than elsewhere, reaching a height of about 12 mi.
Pressure Pressure AreasAreas
Pressure Pressure AreasAreas
Air sinks over a high-pressure center that moves away from the center on the surface, veering to the right in the Northern Hemisphere to create a clockwise circulation pattern.
Air moves toward a low-pressure center on the surface, rising over the center. As air moves toward the low-pressure center on the surface, it veers to the left in the Northern Hemisphere to create a counterclockwise circulation pattern.
Air sinks over a high-pressure center that moves away from the center on the surface, veering to the right in the Northern Hemisphere to create a clockwise circulation pattern.
Air moves toward a low-pressure center on the surface, rising over the center. As air moves toward the low-pressure center on the surface, it veers to the left in the Northern Hemisphere to create a counterclockwise circulation pattern.
“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”
Weather and ClimateWeather and ClimateWeather and ClimateWeather and Climate
DefinitionDefinitionDefinitionDefinition
Weather is a description of the changeable aspects of the atmosphere, the temperature, rainfall, pressure, and so forth, at a particular time. These changes usually affect your daily life one way or another, but some of them seem more inconvenient than others.
Weather is a description of the changeable aspects of the atmosphere, the temperature, rainfall, pressure, and so forth, at a particular time. These changes usually affect your daily life one way or another, but some of them seem more inconvenient than others.
Air MassesAir MassesAir MassesAir Masses
Polar air massAn air mass that moves from a cold
regionTropical Air Mass
An air mass that moves from a warm region
Continental Air MassMoves in from a land mass
Maritime Air MassMoves in from over an ocean
Polar air massAn air mass that moves from a cold
regionTropical Air Mass
An air mass that moves from a warm region
Continental Air MassMoves in from a land mass
Maritime Air MassMoves in from over an ocean
Air Mass TypesAir Mass TypesAir Mass TypesAir Mass Types
Temperature/Moisture
Hot Cold
Wet Tropical Maritime
Polar Maritime
Dry Tropical Continental
Polar Continental
Current WeatherCurrent WeatherCurrent WeatherCurrent Weather
“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”
Clouds and StabilityClouds and StabilityClouds and StabilityClouds and Stability
Types of CloudsTypes of CloudsTypes of CloudsTypes of Clouds
Cumulus (heaped)Stratus (layered)Cirrus (curled)Nimbus (rain)
Cumulus (heaped)Stratus (layered)Cirrus (curled)Nimbus (rain)
How a Cloud FormsHow a Cloud FormsHow a Cloud FormsHow a Cloud Forms Temperature and Dewpoint Converge Water Condenses on Particles (Dirt, Dust, Smoke) Fog is a cloud very near to the surface
Temperature and Dewpoint Converge Water Condenses on Particles (Dirt, Dust, Smoke) Fog is a cloud very near to the surface
PrecipitationPrecipitationPrecipitationPrecipitation
Precipitation is water in the liquid or solid form that returns to the surface of the earth. The precipitation you see here is liquid, and each raindrop is made from billions of the tiny droplets that make up the clouds. The tiny droplets of clouds become precipitation by merging to form larger droplets or by the growth of ice crystals that melt while falling.
Precipitation is water in the liquid or solid form that returns to the surface of the earth. The precipitation you see here is liquid, and each raindrop is made from billions of the tiny droplets that make up the clouds. The tiny droplets of clouds become precipitation by merging to form larger droplets or by the growth of ice crystals that melt while falling.
This figure compares the size of the condensation nuclei to the size of typical condensation droplets. Note that 1 micron is 1/1,000 mm.
This figure compares the size of the condensation nuclei to the size of typical condensation droplets. Note that 1 micron is 1/1,000 mm.
Condensation Nucleus (0.2 microns)
Average Cloud Droplet (20 microns)
Large Cloud Droplet (100 microns)
Drizzle Droplet (300 microns)
Average Rain Drop (2000 microns)
StabilityStabilityStabilityStability
Air may be:Unstable (vertically)
Cumulus cloudsStable (vertically)
Stratus clouds
Air may be:Unstable (vertically)
Cumulus cloudsStable (vertically)
Stratus clouds
CumulusCumulusCumulusCumulus
Fair weather
0
500
1000
1500
2000
19 21 23 25 27 T(°C)
Alti
tud
e (f
t.)
In thermal3 deg/1000 ft
Std. Conditions2 deg/1000 ft
Lapse RateLapse RateLapse RateLapse Rate
The average lapse rate (rate of cooling) is 2° C per 1,000 feet or 3.5° F per 1,000 feet
In order to calculate the base of thermal driven cumulus clouds, divide the temperature / dewpoint spread by the lapse rate (4.4 ° F per 1,000 feet )
The average lapse rate (rate of cooling) is 2° C per 1,000 feet or 3.5° F per 1,000 feet
In order to calculate the base of thermal driven cumulus clouds, divide the temperature / dewpoint spread by the lapse rate (4.4 ° F per 1,000 feet )
AltocumulusAltocumulusAltocumulusAltocumulus
Mackerel sky
Altocumulus at SunriseAltocumulus at SunriseAltocumulus at SunriseAltocumulus at Sunrise
0
2000
4000
6000
8000
10000
12000
14000
16000
0 2 4 6 8 10
T (°C)
Alt
itu
de
(ft.
)Temperature InversionTemperature InversionTemperature InversionTemperature Inversion
Fog is a cloud very near to the surfaceFog is a cloud very near to the surfaceFog is a cloud very near to the surfaceFog is a cloud very near to the surface
Types of FogTypes of FogTypes of FogTypes of FogRadiation (ground) fogAdvection fog
Requires windWarm air over cold land or water
Upslope (orographic) fogRequires wind
Steam fogLake or ocean source of waterCold air over warm water
Precipitation fog (rain fog)
Radiation (ground) fogAdvection fog
Requires windWarm air over cold land or water
Upslope (orographic) fogRequires wind
Steam fogLake or ocean source of waterCold air over warm water
Precipitation fog (rain fog)
Radiation FogRadiation FogRadiation FogRadiation Fog
From the AirFrom the AirFrom the AirFrom the Air
Advection FogAdvection FogAdvection FogAdvection Fog
Upslope FogUpslope FogUpslope FogUpslope Fog
Upslope FogUpslope FogUpslope FogUpslope Fog
Most types of fog form in stable atmospheric conditions. The exception is steam fog,shown in this picture of Maligne Lake, Alberta, Canada, just after sunrise in latesummer. The land cools off overnight while the water retains heat from the summer. Asthe cooled air slips over the lake, heat and moisture are added from below, resulting in afog that twists and writhes-- hence the term "steam fog".
Steam FogSteam FogSteam FogSteam Fog
OrchardOrchardOrchardOrchard
Fans like this one are used to mix the warmer, upper layers of air with the cooling air in the orchard on nights when frost is likely to form.
Fans like this one are used to mix the warmer, upper layers of air with the cooling air in the orchard on nights when frost is likely to form.
StratocumulusStratocumulusStratocumulusStratocumulus
Ice possible in the topsIce possible in the tops
Stratocumulus from aboveStratocumulus from aboveStratocumulus from aboveStratocumulus from above
StratocumulusStratocumulusStratocumulusStratocumulus
Red sky in the morning, sailors take warning
Red sky at night, sailors’ delight—only applies in the tropics
Red sky in the morning, sailors take warning
Red sky at night, sailors’ delight—only applies in the tropics
Types of CloudsTypes of CloudsTypes of CloudsTypes of Clouds
Cumulus (piled up)Stratus (layered)Cirrus (curled)Nimbus (rain)
Cumulus (piled up)Stratus (layered)Cirrus (curled)Nimbus (rain)
CirrusCirrusCirrusCirrus
Overrunning moistureOverrunning moisture
CirrostratusCirrostratusCirrostratusCirrostratus
Moisture increasingMoisture increasing
CirrostratusCirrostratusCirrostratusCirrostratus
Hazy circle round the moon
Means that rain is coming soon!
CirrostratusCirrostratusCirrostratusCirrostratus
Condensation Trails (Contrails)
CirrocumulusCirrocumulusCirrocumulusCirrocumulus
ThunderstormsThunderstormsThunderstormsThunderstormsThunderstorms require
Unstable air Moisture Lifting mechanism
T-storms always have lightning Thunder is the sound of lightning T-storms are reported when thunder is heard
Only true for manned observation posts Automatic Reporting (AWOS) detects lightning
discharge
Thunderstorms require Unstable air Moisture Lifting mechanism
T-storms always have lightning Thunder is the sound of lightning T-storms are reported when thunder is heard
Only true for manned observation posts Automatic Reporting (AWOS) detects lightning
discharge
Three stages in the life of a thunderstorm cell. (A) The cumulus stage begins as warm, moist air is lifted in an unstable atmosphere. All the air movement is upward in this stage.
Three stages in the life of a thunderstorm cell. (A) The cumulus stage begins as warm, moist air is lifted in an unstable atmosphere. All the air movement is upward in this stage.
(B) The mature stage begins when precipitation reaches the ground. This stage has updrafts and downdrafts side by side, which create violent turbulence.
(B) The mature stage begins when precipitation reaches the ground. This stage has updrafts and downdrafts side by side, which create violent turbulence.
(C) The final stage begins when all the updrafts have been cut off, and only downdrafts exist. This cuts off the supply of moisture, and the rain decreases as the thunderstorm dissipates. The anvil-shaped top is a characteristic sign of this stage.
(C) The final stage begins when all the updrafts have been cut off, and only downdrafts exist. This cuts off the supply of moisture, and the rain decreases as the thunderstorm dissipates. The anvil-shaped top is a characteristic sign of this stage.
LightningLightningLightningLightning
Different parts of a thunderstorm cloud develop centers of electric charge. Lightning is a giant electric spark that discharges the accumulated charges.
Different parts of a thunderstorm cloud develop centers of electric charge. Lightning is a giant electric spark that discharges the accumulated charges.
ThunderstormsThunderstormsThunderstormsThunderstorms
Types of thunderstormsAir massFrontal Upslope (orographic)
Types of thunderstormsAir massFrontal Upslope (orographic)
HailHailHailHail
These hailstones fell from a thunderstorm in Iowa, damaging automobiles, structures, and crops.
These hailstones fell from a thunderstorm in Iowa, damaging automobiles, structures, and crops.
CumulonimbusCumulonimbusCumulonimbusCumulonimbus
Distance to a Storm
Distance to a Storm
Thunderstorm
Bad IdeaBad IdeaBad IdeaBad Idea
CumulonimbusCumulonimbusFrom SpaceFrom Space
CumulonimbusCumulonimbusFrom SpaceFrom Space
Boundaries between air Boundaries between air masses = frontsmasses = fronts
Boundaries between air Boundaries between air masses = frontsmasses = fronts
ColdWarm StationaryOccluded
ColdWarm StationaryOccluded
Types of FrontsTypes of Fronts
Weather FrontsWeather FrontsWeather FrontsWeather Fronts
FrontA boundary between two different air
massesCold Front
When a cold air mass moves into a warmer area, displacing the warm air mass
Provides lift to adiabatically cool the warm air, resulting in towering cumulus and thunderclouds.
FrontA boundary between two different air
massesCold Front
When a cold air mass moves into a warmer area, displacing the warm air mass
Provides lift to adiabatically cool the warm air, resulting in towering cumulus and thunderclouds.
Cold Front PixCold Front PixCold Front PixCold Front Pix
A cold air mass is similar to a huge, flattened bubble of cold air that moves across the land. The front is the boundary between two air masses, a narrow transition zone of mixing.
A front is represented by a line on a weather map, which shows the location of the front at ground level.
A cold air mass is similar to a huge, flattened bubble of cold air that moves across the land. The front is the boundary between two air masses, a narrow transition zone of mixing.
A front is represented by a line on a weather map, which shows the location of the front at ground level.
Warm FrontWhen a warm air mass moves into an
area, displacing the cold air massA gently sloping front as the Warm air
moves over top of the cooler air.Stationary Front
When the edge of a front ceases to advance
Warm FrontWhen a warm air mass moves into an
area, displacing the cold air massA gently sloping front as the Warm air
moves over top of the cooler air.Stationary Front
When the edge of a front ceases to advance
Warm Front PixWarm Front PixWarm Front PixWarm Front Pix
An idealized warm front, showing a warm air mass overriding and pushing cold air in front of it. Notice that the overriding warm air produces a predictable sequence of clouds far in advance of the moving front.
An idealized warm front, showing a warm air mass overriding and pushing cold air in front of it. Notice that the overriding warm air produces a predictable sequence of clouds far in advance of the moving front.
Occluded FrontOccluded FrontOccluded FrontOccluded Front
One that has been lifted completely off the ground
Has a low pressure center and cyclonic activity
One that has been lifted completely off the ground
Has a low pressure center and cyclonic activity
CyclonesCyclonesCyclonesCyclones
CycloneA low pressure area with winds
moving into the low pressure area and being forced upward.
Friction and the Coriolis effect cause the air to move to the right of the direction of movement.
AnticycloneA high pressure center
CycloneA low pressure area with winds
moving into the low pressure area and being forced upward.
Friction and the Coriolis effect cause the air to move to the right of the direction of movement.
AnticycloneA high pressure center HHHH
LLLL
Hurricane JohnHurricane JohnHurricane JohnHurricane John
This is a satellite photo of hurricane John, showing the eye and counterclockwise motion
This is a satellite photo of hurricane John, showing the eye and counterclockwise motion
Storm TracksStorm TracksStorm TracksStorm Tracks
Cyclonic storms usually follow principal storm tracks across the continental United States in a generally easterly direction. This makes it possible to predict where the low-pressure storm might move next.
Cyclonic storms usually follow principal storm tracks across the continental United States in a generally easterly direction. This makes it possible to predict where the low-pressure storm might move next.
“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”
Weather ForecastingWeather ForecastingWeather ForecastingWeather Forecasting
Computer ModelsComputer ModelsComputer ModelsComputer Models
Weather PredictionsWeather PredictionsWeather PredictionsWeather Predictions
Weather predictions are based on information about air masses, fronts, and associated pressure systems in an area.
This information is used to produce a model of behavior for weather using a computer. Many models are used and then summarized
when the different models agree fairly closely to a model of the weather.
Weather predictions are based on information about air masses, fronts, and associated pressure systems in an area.
This information is used to produce a model of behavior for weather using a computer. Many models are used and then summarized
when the different models agree fairly closely to a model of the weather.
Surface Pressure/Precipitation PlotSurface Pressure/Precipitation Plot
PredictedPredicted
ActualActual
Forecast for todayForecast for todayForecast for todayForecast for today
SupercomputersSupercomputersSupercomputersSupercomputers
Supercomputers make routine weather forecasts possible by solving mathematical equations that describe changes in a mathematical model of the atmosphere. This "fish-eye" view was necessary to show all of this Cray supercomputer at CERN, the European Center of Particle Physics.
Supercomputers make routine weather forecasts possible by solving mathematical equations that describe changes in a mathematical model of the atmosphere. This "fish-eye" view was necessary to show all of this Cray supercomputer at CERN, the European Center of Particle Physics.
Example of Atmospheric Example of Atmospheric RReeffrraaccttiioonn
Example of Atmospheric Example of Atmospheric RReeffrraaccttiioonn
Where’s the pot of goldWhere’s the pot of gold??