Comprehensive Guide to Air Masses, Fronts, and Severe Weather Phenomena in Meteorology

What is an air mass?

A large body of air (500-1500 miles in diameter) characterized by relatively uniform temperature and moisture.

What do the first and second letters in air mass designations represent?

The first letter indicates moisture (m for maritime/moist, c for continental/dry) and the second letter indicates temperature (A for Arctic, P for Polar, T for Tropical, E for Equatorial).

What conditions are necessary for the development of air masses?

They require large, flat areas with light upper-level winds, typically found in high-pressure zones.

How are air masses modified?

They are modified by the surface they travel over through thermodynamic (heating/cooling) and mechanical (lifting) processes.

What type of air mass is cP and where does it originate?

Continental Polar (cP) air mass originates from Central Canada and brings cold, dry, stable air.

What type of air mass is mT and what does it bring?

Maritime Tropical (mT) air mass comes from the Gulf of Mexico and brings warm, humid, unstable air, which is the main source of precipitation for the Eastern U.S. and Texas.

What is a cold front?

A boundary where cold air replaces warm air, characterized by a steep slope that causes rapid lifting and narrow bands of violent weather.

What is a warm front?

A boundary where warm air replaces cold air, characterized by a gentle slope leading to widespread, light-to-moderate precipitation.

What happens during an occluded front?

A cold front catches up to and overtakes a warm front.

What is a stationary front?

A boundary where neither air mass is strong enough to displace the other, leading to extended cloudiness and rain.

What is a dry line?

A boundary based on humidity that separates dry (cT) air from moist (mT) air, commonly seen in Texas.

What are Mid-Latitude Wave Cyclones (MLWCs)?

Large-scale low-pressure (cyclonic) systems influenced by the jet stream, forming along the polar front and traveling east.

What are the three stages of air mass thunderstorms?

Cumulus, Mature, and Dissipating.

What causes frontal thunderstorms?

Forced uplift along a frontal boundary, usually a cold front.

What is a squall line?

A narrow band of high-speed thunderstorms that often develops 60-180 miles in advance of a cold front.

What is a gust front?

The leading edge of cold air that pours out of a thunderstorm and spreads along the ground, acting like a mini cold front.

What are downbursts?

Exceptionally strong downdrafts of air from a cumulonimbus cloud, appearing as a starburst pattern on radar.

What is a derecho?

A widespread, long-lived straight-line wind storm associated with a band of rapidly moving thunderstorms.

What are the characteristics of lightning?

A typical lightning strike carries 100 million volts and reaches temperatures of 54,000°F.

What causes thunder?

The rapid expansion of air when heated by lightning, creating a shock wave.

What types of lightning exist?

Intracloud, cloud-to-cloud, and cloud-to-ground.

What are the three types of lightning strikes?

Intracloud, Cloud-to-cloud, and Cloud-to-ground.

How many fatalities are caused by lightning strikes per year in the U.S. and Canada?

Roughly 100+ people.

How many fires does lightning start annually?

Approximately 10,000 fires per year.

What is a Fulgurite?

A glass tube formed when lightning hits sand.

When do most lightning deaths occur?

After the storm has passed, often when it is not raining.

What causes a lightning strike?

A discharge of electricity to equalize charge separation within clouds or between cloud and ground.

What is a mesocyclone?

A vertical column of cyclonically rotating air within a supercell.

What are the three categories of tornadoes based on EF rating?

Weak (EF0-EF1), Strong (EF2-EF3), and Violent (EF4-EF5).

What percentage of tornadoes are classified as weak (EF0-EF1)?

Approximately 80%.

What is the Enhanced Fujita (EF) Scale used for?

To estimate wind speeds based on damage indicators.

What conditions are required for hurricane formation?

Warm ocean water (> 80°F), Coriolis Force, and light winds aloft.

What is the minimum wind speed for a storm to be classified as a hurricane?

At least 74 mph.

What is the Saffir-Simpson Scale used for?

To categorize hurricanes from 1 to 5 based on wind speed and damage potential.

Why is there no Category 6 hurricane?

Category 5 is defined as 'total destruction,' and higher categories would not provide additional practical meaning.

What was the deadliest U.S. natural disaster?

The Galveston hurricane of 1900.

What is a 100-year flood?

A flood that has a 1% chance of occurring in any given year.

Why is the term '100-year flood' considered confusing?

It suggests safety for 99 years after one occurs, but it is a statistical probability.

What factors contribute to flooding in Southeast Texas?

High precipitation intensity, high clay content in soils, and development of impervious surfaces.

What is the typical peak tornado activity month in Texas?

May.

What is the significance of the term 'Right-Front Quadrant' in hurricanes?

It is where the strongest winds and rain are located relative to the storm's motion.