Air Masses and Fronts Study Notes
AIR MASSES AND FRONTS
Page 1
- Introduction to the topic of air masses and fronts.
Page 2
Air Masses
- Definition: A large body of air with similar temperature and humidity characteristics.
- Formation Conditions: Forms in regions with light winds and generally uniform topography, such as arctic regions, oceans, and expansive flat lands.
Classification of Air Masses by Source Regions:
- P: Polar
- T: Tropical
- A: Arctic
- m: Maritime (moist air)
- c: Continental (dry air)
Page 3
Air Mass Classifications & Characteristics
- Arctic (A): Extremely cold, dry, stable; often ice- and snow-covered surfaces.
- Polar (P): Cold, dry, stable.
- Tropical (T):
- Continental (c):
- cA: Extremely cold, dry, stable air.
- cP: Cold, dry, stable air.
- cT: Hot, dry, stable aloft; unstable surface air.
- Maritime (m):
- mP: Cool, moist, unstable air.
- mT: Warm, moist; usually unstable air.
- Comparative Note: Arctic air is colder than polar air, despite seeming counterintuitive.
Page 4
- Graphical representation of air masses as outlined in previous content.
Page 5
Continental Arctic (cA) Air Mass
- Associated with the “Polar Vortex,” known to produce record-breaking low temperatures.
Page 6
- Unorganized data presumably relating to weather patterns centered on temperatures and pressure readings.
Page 7
Continental Polar (cP) Air Mass
- Characteristics: Cold, dry, stable air forming in Canada.
- Common Effects: Typical air mass behind a cold front moving Southeast; leads to lake-effect snow phenomena as cold air moves over warmer water.
Page 8
Lake Effect Snow
- Occurs on the downwind side of the Great Lakes.
- **Process: **Cold air moves over relatively warm lake waters, absorbing water vapor, leading to rising motion due to heat addition and terrain slowing, resulting in snowfall on the downwind shore.
Page 9
- A map of the areas affected by lake-effect snow including WI, MI, IL, IN, MO, NY, and PA.
Page 10
Maritime Polar (mP) Air Mass
- Characteristics include cool, moist, and somewhat unstable air.
- Source: Primary source from the Pacific; lifted by mountains on the west coast, contributing to rain and snow, or from the Atlantic via low-pressure systems like Nor’easters.
Page 11
Maritime Tropical (mT) Air Mass
- Characteristics: Warm, moist, unstable.
- Source Regions: Gulf of Mexico and tropical Atlantic, feeding thunderstorms in the eastern and central U.S.
- Significant Weather Events:
- The “Pineapple Express” from the tropical Pacific into California, known for severe weather, mountain snowpack, and flooding.
Page 12
Continental Tropical (cT) Air Mass
- Characteristics: Hot and dry with stable conditions aloft but unstable at the surface.
- Occurrence: Present only in summer in the Southwest; typically results in minimal clouds and precipitation, but prolonged presence can lead to drought (example: July 2005 heat wave).
Page 13
Source Regions: Great Plains
- Question: Why is the Great Plains NOT a source region for air masses? Options include:
A. Too hot
B. Too dry
C. Too windy
D. Too high
E. Too diverse
Page 14
- Weather data regarding Maritime Tropical conditions ahead of a tropical cyclone.
Page 15
- Data depiction of atmospheric conditions at 700 hPa for August 16, 2007.
Page 16
- Atmospheric conditions for August 18, 2007 providing pressure readings.
Page 17
- Continued readings of atmospheric data from August 19, 2007.
Page 18
- Additional atmospheric readings for August 19, 2007 focusing on upper air conditions.
Page 19
Air Mass Identification
- Analysis from Plymouth State Weather Center detailing surface pressure readings and air mass observations for January 10, 2006, showcasing parameters for identification.
Page 20
Cold Weather Statement
- Example Statement: “It hasn’t been this cold in College Station since 1899!”, likely referring to an air mass.
- Air Mass Likely: Options include:
A. cT
B. mT
C. cA
D. cP
E. mP
Page 21
Air Mass Pressure Map
- A brief representation showing various pressure readings and conditions surrounding air masses.
Page 22
Fronts
- Definition: The boundary between air masses characterized by differences in temperature and humidity.
- Key Features: Occurs at the ground with symbols indicating the direction of movement.
- Types of Fronts: Cold fronts, warm fronts, stationary fronts, and occluded fronts.
Page 23
- Concludes the first day’s study material.
Page 24
Scale Relation of Air Masses and Fronts
- Question: Air masses and fronts fit which scale? Possible Answers:
A. Global scale
B. Macroscale
C. Synoptic scale
D. Mesoscale
E. Microscale
Page 25
Cold Fronts
- Characteristics: A dome of dense cold air replacing warm air. The leading edge of a cold front is steep, often leading to strong upward motion.
Page 26
- Visual or graphical representation of cold fronts with relevant data.
Page 27
Effects of Cold Front Passage
| Condition | Before Passage | During | After |
|---|
| Wind | S or SW | Gusty, shifting | W or NW, often strong |
| Temperature | Warm | Sudden drop | Dropping |
| Pressure | Falling | Minimum reached | Sharp rise |
| Clouds | Ci, Cs, Ac, then Cb | Tcu or Cb | Cu or Sc |
| Precipitation | Brief showers | Heavy showers, severe | Clearing |
| Dew Point | High | Drops sharply | Lowering |
Page 28
Warm Fronts
- Characteristics: Warm air replacing cool air; the slope is relatively gentle leading to broader areas of upward motion.
- Movement: Generally moves more slowly than cold fronts.
Page 29
- Additional data points or graphical representations concerning warm fronts.
Page 30
Effects of Warm Front Passage
| Condition | Before Passage | During | After |
|---|
| Wind | S or SE | Variable | S or SW |
| Temperature | Cool or cold | Steady rise | Warming |
| Pressure | Falling | Leveling off | Slight rise, then fall |
| Clouds | Ci, Cs, As, Ns, St, then fog | Stratus Clearing | None |
| Precipitation | Light rain, snow, sleet, freezing rain | Drizzle or none | None |
| Dew Point | Steady rise | Steady | Rising, then steady |
Page 31
Identification of Warm Front Characteristics
- Question: What color and shape indicates a warm front?
- Student Interaction: Type in an answer.
Page 32
Stationary Fronts
- Characteristics: Self-explanatory, does not move much.
- Effects: Can lead to flooding in instances of moisture on both sides where rain persists for several days along the front.
Page 33
Occluded Fronts
- Description: Occurs when a cold front overtakes a warm front.
- Graphic Representation: Illustrated as a purple line with triangles and semi-circles.
- Types: Cold occlusion and warm occlusion.
Page 34
Cold vs. Warm Occluded Fronts
- Cold Occlusion: Very cold air overtaking warm air.
- Warm Occlusion: Cool maritime tropical air merging with cooler continental polar air.
- Visual Depiction: Differentiation between types (A, B) with underlying explanations.
Page 35
Identification of Occluded Front Types
- Interactive element prompting viewers to distinguish between types of occluded fronts.
Page 36
Finding a Front Characteristics
- Low pressure noted by a “kink” in isobars.
- Sharp change noted in temperature along the front.
- Sharp change in dew point detected.
- Clear shift in wind direction observed.
- Clouds and precipitation presence.
- Example Utilization: Link to professional observations (e.g., WPC surface analysis).
Page 37
Real-world Front Analysis
- Live examples including surface analysis and radar overlays provided through links for observing current weather patterns.
Page 38
Fastest Moving Front During Occlusion Developments
- Question: Which front is moving faster as an occlusion develops?
- Possible answers: A. Cold B. Warm C. Stationary D. Occluded
Page 39
- Concludes the second day’s study materials.
Page 40
Mixed Precipitation and Fronts
- Stationary and Warm Fronts can relate to ice storms and varied precipitation types during winter.
- Cold Air Damming: Explains effects in mountainous regions, emphasizing rain patterns.
Page 41
Risk of Freezing Rain with Warm Fronts
- Profile View illustrating the temperature gradient and precipitation types with a warm front.
- Layer Descriptions: 0 °C levels impacting the formation of freezing rain and associated precipitation types like ice pellets and snow.
Page 42
- Continues exploring possibilities of light snow and freezing rain in cold damp air.
Page 43
Cold Air Damming
- Dynamics: Explanation of how mountains impede warm air circulation leading to complex precipitation events.
Page 44
Warm Front and Mixed Precipitation
- Driving Scenario: Anticipating mixed precipitation when approaching a warm front, outlining possible transitions from rain to snow.
Page 45
Upper-Air Fronts
- Description of how tropopause dips downward, influencing surface weather patterns.
- Relevance of Jet Core: Air motion depicted in relation to upper-level fronts.
Page 46
Upper-Level Air Motion Explanation
- Graphical representation of upper-level temperatures and air motion surrounding fronts.
Page 47
Other Boundaries
- Dryline: Significant as a boundary separating very hot, dry air from warm, moist air common in the southern Plains, often resulting in severe storms.
Page 48
Pressure Troughs
- Description of pressure trough characteristics indicating minimal temperature gradient despite visible changes in isobars or wind shifts.
Page 49
Current Fronts and Weather Analysis
- Live access to surface analyses and weather forecasts through provided links for evaluation of weather conditions.
Page 50
Factors Influencing Air Mass Movement
- Prompt encouraging student input to identify potential factors that encourage air mass movement.
Page 51
Homework Assignment
- Instructs students to identify three different air masses affecting weather in Texas, detailing origin, type of front marking it, and resulting weather conditions to encompass understanding of regional meteorology.