Meteorology Notes Part II. Atmosphere Composition and Structure Effect of Earth’s shape and tilt on weather and seasons Air Mass Types and Formation Global Wind Systems and Ocean Currents. Atmosphere Composition. About 99% of the atmosphere is composed of nitrogen and oxygen. 21% is oxygen
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Atmosphere Composition and Structure
Effect of Earth’s shape and tilt on weather and seasons
Air Mass Types and Formation
Global Wind Systems and Ocean Currents
-Gradual decrease in temperature from bottom to top because it is heated by the Earth’s surface
-Layer closest to the Earth’s surface
-Contains the most mass of the atmosphere
-Most weather (clouds, etc.) takes place here
-Layer where most pollution collects
-The top of the troposphere is called the Tropopause (9km – 16km); Gradual decrease in temperature stops.
-Located above the tropopause
-Layer primary made up of concentrated ozone with the majority near the stratopause
-Ozone absorbs ultraviolet radiation causing temperature to rise as height increases from the bottom to the top of the stratosphere.
The stratopause is located above the stratosphere where temperature stops increasing
Located above the stratopause
No ozone = no gases to absorb radiation and warm the layer = gradual decrease in temperature
Mesopause is the boundary between the mesosphere and the next layer, the thermosphere.
Minute portion of atmosphere’s mass
Air again increases in temperature in this layer, this time to more than 1000 degrees Celsius
Exosphere & Ionosphere
The ionosphere is part of the thermosphere.
The ionosphere is made up of electrically charged particles and layers of progressively lighter gases.
-Interaction of the solar wind from the sun with the ionosphere creates the Auroras
The Exosphere, above the Thermosphere, is so thin that most scientists actually consider this the beginning of space.
Light gases, like helium and hydrogen, are found in this layer.
There is no clear boundary between the atmosphere and outer space.
Earth’s axis is tilted relative to the ecliptic at approximately 23.5 degrees
-As Earth orbits the sun this tilt angle never changes - the Earth’s axis stays fixed in space.
-Our seasons are created by this tilt and the Earth’s revolution around the Sun.
-As the Earth moves around the sun each year, the altitude of the sun in our sky changes. At the solstices, the axis either points directly at or away from the Sun.
1.) Summer solstice- the Sun’s maximum altitude in the sky.
2.) Winter solstice- the Sun’s lowest altitude in the sky.
-At the equinoxes, the Earth’s axis is beside the Sun, not towards or away.
1.) As a result, both hemispheres receive equal amount of light. The lengths of day and night are also equal
2.) There are two equinoxes – autumnal and vernal.
-Because of the tilt, we have some special latitudes on Earth.
a. On the equinoxes, the Sun is directly overhead on the equator.
b. On the Summer Solstice, around June 20, the Sun is directly overhead at 23.5º N. latitude, the Tropic of Cancer.
c. On the Winter Solstice, around Dec. 20, the Sun is directly overhead at 23.5º S. latitude, the Tropic of Capricorn.
cT – continental tropic
– warm + dry
mT – maritime tropic
– warm + humid
cP – continental polar
– cold + dry
mP – maritime polar
– cold + humid
A – artic – very cold and dry – associated with high pressure
Notice: Each type tells you the source region and the temperature
The Coriolis effect is the APPARENT deflection of air particles due to the rotation of the Earth.
Air in the northern hemisphere is deflected to the right.
Air in the southern hemisphere is deflected to the left.
Horse Latitudes – at 30 degrees N and S latitude where there are light winds and clear skies
Doldrums (ITCZ) – near the equator where there are frequent storms and heavy rains
http://www.pbs.org/wgbh/nova/vanished/jetstream.html characteristics of the area over which it forms