Download 8 - Meteorology - Simone Damiano

S c i e n c e s
Meteorology
Key words: Atmosphere, Ozone, Water vapor, solar radiation, Condensation, Evaporation, Humidity,
Dew-Point Temperature, Cirrus Clouds, Stratus Clouds, Cumulus Clouds,
Pressure in the Atmosphere
Atmospheric pressure is the weight of the air column above a specific area. At sea level this is about 1
Kg/cm2.
Air pressure is measured using a barometer. There are two types of barometers:
Mercury Barometer
Aneroid Barometer
Pressure in the Atmosphere
Global circulation
Wind is the flow of gases on a large scale.
Winds are caused by differences in pressure, always moving from regions
with higher pressure (H) toward low pressure regions (L). On our planet ,
during this path, the air is deflected by the Coriolis effect, except on the
equator.
Globally, the two major forces driving the atmospheric circulation are:
1 - The differences in heating between the equator and the poles (resulting in
differences in atmospheric pressure). The larger is the difference the stronger the is
wind flow.
2 - The rotation of the planet, resulting in the Coriolis Force. The Coriolis force causes
the winds to bend to the right in the Northen Hemisphere and to the left in the
Southern Hemisphere
Global circulation
L
H
Westerlies
H
Northeasterly
Trade winds
L
Southeasterly
Trade winds
H
Westerlies
L
Planetary wind and moisture belt in the atmosphere
Planetary wind and moisture belt in the atmosphere
Cyclones and Anticyclones
Cyclones
Anticyclones
Ocean Currents
Land breeze and sea breeze
A local effect is the breeze.
Daytime heating along a beach area warms the land and water at different rates. The land heats up much
faster than the water does. The land then heats up the air above it. The air becomes less dense and rises. The
cooler air over the water moves in to take its place. The heated air eventually cools and moves to take the
place of the air that was over the water. This convection cell that is created causes a sea breeze for anyone
who is on the beach.
At night, the land cools off faster than the water and the air reverses direction. A land breeze is formed. The
land breezes are generally weaker than sea breezes due to the fact that water cools off more slowly than
land heats up.
Remember that the winds are named
for the direction that they came from
Monsoons
For the same reason that sea and land breezes form, largerscale winds are created between continents and oceans. In
the summertime, the oceans are cooler than the continents.
The areas of cooler, sinking air over the oceans cause high
pressure to be formed. Areas of lower pressure are formed
over the land.
In some areas of the world, seasonal
winds are created. These monsoon
winds cause wet and dry seasons. In
India, the winds coming off of the Indian
Ocean create extended periods of
heavy rain. When the winds shift and
come down from the Himalayan
Mountains, much drier conditions are
experienced.