This document discusses air masses and their types. It defines an air mass as a large body of air with similar temperature and humidity that forms in stable source regions. There are two main types of air masses - continental and maritime. Continental air masses originate over landmasses and are usually dry, while maritime air masses originate over large bodies of water and are usually moist. Specific continental air masses include tropical (cT), mid-latitude (cM), and polar (cP). Maritime air masses include tropical (mT), mid-latitude (mM), and polar (mP). Each air mass has distinct characteristics depending on its source region and how it interacts with terrain as it moves across regions.

1. Subject: Geography
Class: MSc (Ist)
Roll# 7826
Submitted to: Mam Nusrat parveen
Submitted by: Fakhara younas
Semester: Ist “morning”
Department of Geography
GC University Fsd

2. AIR MASSES AND ITS TYPES
AIR MASSES:
An air mass is large body of air with similar
temperature and humidity.
Air masses form in stable “source regions” such as
in the sub tropics or near to the poles.
A region under the influence of an air mass will
probably experience generally constant weather
conditions, a situation referred to as “air mass
weather”.

3. TYPES OF AIR MASSES:
CONTINENTAL AIR MASS
MARITIME AIR MASS
t Tropical w warmer
p Polar k Kalt (cold)
m Maritime s stable
c continental u unstable
INDEX

4. CONTINENTAL AIR MASS:
• A continental air mass has a uniform temperature and moisture profile.
As with all air masses, the characteristics of the air are the same as the
region from which the large mass of air originated. In the case of any air
mass labeled as continental, the air originated over a large landmass and
is usually dry.
• MARITIME AIR MASSES:
• The maritime tropical air mass of originates Atlantic ocean east of
Florida over the Bahamas Ireland .over the pacific ocean. Lower
California is, a source region of another maritime tropical (mt) air
mass. A maritime or oceanic air mass has a uniform temperature
and moisture profile. The characteristics of the air mass are the
same as the region from which the large mass of air originated. In
the case of any air mass labeled as maritime, the air originated over
a large body of water and is usually moist.

5. TYPES OF CONTINENTAL AIR MASSES
1. TROPICAL (cT)
2. MID LATITDUE (CM)
3. POLAR (CP)
TROPICAL (cT)
A hot dry continental tropical (cP air mass originates over Northern Mexico,
Western Texas, New Mexico and Arizona during the summer. The source
region for cT air is the desert South west, the high plains and Mexico. The air
has low dew points and warm to hot afternoon temperatures but with mild
nighttime temperature. Due to the buoyancy and elevation of cT air across
North America, this air will advect into the mid-levels of the atmosphere once
it moves out of its source region. This creates a cap of mild dry air. If this air
adverts over PBL MT air, the severe thunderstorm threat increases
significantly. The boundary of cT is most noticeable with the creation of a dry
line. A dry line separates mT air from cT air. Depending on the strength of the
dry line, convergence along the dry line and the dynamics above the dry
line, severe thunderstorms can form near a dry line boundary.

6. POLAR (cP):
• The continental polar (cp) air mass of North America, originates
over north-central Canada. This air mass has low dew points, cold
temperatures and a high degree of stability. The denseness of cP air
creates surface high pressure and a trough aloft, especially when cP
air moves into lower latitudes. Precipitation in association with cP
air is usually light due to the dryness and low moisture capacity of
the air. Precipitation is most common on the "edges" of cP air,
especially where it intersects and displaces mT air. Precipitation
within a cP air mass is elevated and dynamically induced. These
dynamical uplift mechanisms include jet streaks, isentropic
lifting and positive differential vortices advection. Cold surface
temperatures and a dry boundary layer inhibit thermodynamic
convection.

8. TYPES OF MARITIME AIR MASS:
1. TROPICAL (mT)
2. MID LATITUDE(Mm)
3. POLAR (mP)
MARITIME TROPICAL (mT):
The maritime tropical air mass is most often felt in the
Southeast US. In the winter this air mass is shoved toward the equator
but in summer it can cover much of the US east of the Rockies. This air
mass results from the warm waters of the Gulf of Mexico and Gulf
Stream. The warm waters in this region evaporate an enormous
volume of water. Cold water currents tend to stabilize the atmosphere
and produce little evaporation while warm waters destabilize the
atmosphere and add moisture. The warm waters warm the low levels
of the atmosphere.

9. MARITIME POLAR (mP):
• The maritime polar (mP) air mass originates over the north pacific
and bearing strait north Atlantic ocean north American region. The
source region for mP air is over cold ocean currents or high latitude
ocean waters. This air does not have the moisture content as mT air.
Since mP air is always near saturation, orographic lifting of the air
mass can produce widespread rain or snow. This air mass is
notorious for producing fog, drizzle, cloudy weather and long lasting
light to moderate rain. The temperature of MP air ranges from just
above freezing to below 70 ° F. mP air is modified as it moves over
elevated terrain. On the windward side of mountain ranges, MP air
can produce an abundance of rain and snow. Once on the lee side of
mountains, the mP air mass modifies into a continental air mass.
These air masses produce cold fronts but the air is not as cold as
polar or arctic fronts. They are often termed "Pacific fronts.

11. Thank you