5b_AtmosphericWeather

Weather is influenced by a variety of factors, including air masses and atmospheric lifting mechanisms.
Major components of weather systems include:
- Air Masses
- Atmospheric Lifting Mechanisms
- Mid-latitude Cyclonic Systems
- Violent Weather

An air mass is a large body of air that reflects the characteristics of its source region. Examples include:
- Cold Canadian air mass
- Moist tropical air mass
Classification of Air Masses:
- Moisture:
  - Maritime (m): wetter air
  - Continental (c): drier air
- Temperature:
  - Arctic (A)
  - Polar (P)
  - Tropical (T)
  - Equatorial (E)
  - Antarctic (AA)

When air masses migrate, they modify temperature and moisture characteristics.
Examples of modification:
- Warm, humid maritime air moving into cooler continental areas
- Dry, cold continental air from polar regions moving south and east over the Great Lakes.

Convergent Lifting
- Air flows toward an area of low pressure, causing uplift.
- Example: Trade winds converge at the Intertropical Convergent Zone.
Convectional Lifting
- Caused by local surface heating, where cooler air moves over warmer land.
- Includes: urban heat islands and darker soils.
Orographic Lifting
- Air is forced upwards over barriers like mountains.
- Windward side experiences cooling and potential precipitation, while leeward side may experience drying (rain shadow).
Frontal Lifting
- Occurs along boundaries of differing air masses (cold and warm).
- Warm air is lifted over denser, cold air, resulting in precipitation and potential storm activity.

Cyclogenesis: conflict between cold and warm air masses leads to cyclone formation.
Stages of Cyclone:
1. Open Stage: Warm air moves north while cold air advances south.
2. Occluded Stage: Cold air overtakes warm front.
3. Dissolving Stage: Continuous layer of cooler air beneath warmer air.

Cyclonic storms are guided by the jet stream and shift in latitude with changing seasons.
The most significant frontal activity occurs in spring, leading to thunderstorms and tornadoes.

Can develop in various conditions, including air mass instability and orographic lifting.
Characterized by: large water vapor, latent heat release, and cumulonimbus clouds with heavy precipitation, lightning, and potential for tornadoes.

Lightning occurs due to charge differentiation within cumulonimbus clouds, creating a path of electrical discharge.
A lightning stroke can heat the air up to 30,000 °C, causing a rapid expansion that creates thunder.

Hailstones develop in strong updrafts within cumulonimbus clouds, gaining layers of ice as they circulate above and below the freezing level.

Derechos are strong linear winds associated with thunderstorms, capable of causing significant damage.

Begins with unstable warm, moist air beneath a ceiling of cold air.
Abrupt lifting can create a narrow area of intense low pressure, leading to a vortex.
Tornadoes primarily form in areas known as "Tornado Alley."

Develop within tropical air masses and start with a wave of low pressure in trade wind belts.
A hurricane forms when sea temperatures are above 26 °C (79 °F). Key features include:
- Counterclockwise wind rotation in the Northern Hemisphere.
- Strong winds and low pressure lead to storm surges.

Galveston Hurricane of 1900: Category 4 with severe destruction and high fatality rate.
Hurricane Katrina (2005): Category 5 with the highest economic loss in U.S. history.
Hurricane Ike (2008): Notable for its size and destruction as a Category 2 hurricane.