Weather Theory:
Moon is unchanged for thousands of years.
The earth is surrounded by a thin layer of gases, that helps to protect the world from
temperature extremes, and harmful solar radiation.
The atmosphere, is made up of 78% Nitrogen, 21% Oxygen, and 1% various other
gases including Carbon Dioxide, Aragon.
The Troposphere rises up to 60,000 feet at the equator, and as low as 20,000 feet at
the poles.
It is capped by the tropopause that acts as a lid and contains the weather. Outside of
the troposphere beyond the boundary layer of the tropopause is the stratosphere. It
extends up to 22 miles above the earths surface.
The air contains molecules, and warmer air has fewer fast moving molecules, in
comparison to cold air which has more slower moving molecules. Therefore warm
air is less dense than cold air, or rather hot air is lighter, and cold air is heavier.
If we had to connecting rooms and one room had cold air, while the other had hot
air, when we opened the door the cold air would rush into the room with the hot air,
sliding underneath it, and the hot air would slowly replace the cold air in the other
room, until both rooms were even. This illustrates a very basic fundamental function
of weather and also explains wind. The cold air rushing into the warmer room
would create a draft or breeze, just like in the atmosphere when colder air slides
under warmer air. The result is the same thus wind is the result.
The sun will hit the earth and reach the surface, thus heating up the earth. However,
heat from the sun will not hit the earth evenly. There is more distance between
atmosphere layers, and the surface at the poles in comparison to the equator.
Therefore more heat occurs at the equator rather than the poles. Since this happens,
warmer air at the equator rises until it hits the boundry layer of the atmosphere.
When it hits the boundry layer it flows like a current across the layerup to the poles.
However as it gets closer and closer to the poles it cools down, and as the air
becomes more cold it sinks back do to the surface over the poles. This actually
happens in 30 degree segments. From 0 to 30 degrees logitute, and then form 30 to
60 degrees logitude, and then from 60 to the poles.
Coriolis force is the concept that air traveling from the poles will travel in a straight
line however, since the earth is rotating, by the time the air travels to it’s intented
place, it will be deflected to the right.
Atmospheric pressure determines how many air molecules are over a given area.
We use barometers to measure atmospheric pressure.
Areas with less dense air are high pressure areas. Areas with dense air are low
pressure.
Coastal Areas:
Areas with water go through a simulair process. As the sun heats up the surface the
air warms up and flows upward. However the air over the water cools down and
flows inland to replace the rising warm air. AKA a Sea Breeze. As it gets darker at
night the surface cools down and the water is still the same temp, therefore the
water is warmer. The air flow reverses itself, and the colder air flows toward the
water in a downward motion, while the warmer air over the water flows upward
and back toward the land. AKA a land breeze.
Mountainous Areas:
As cold air descends down the mountain range it speeds up and simultaneously
warms up. It eventually becomes warmer than the air that it is flowing underneath
and then will immediately start to rise and shift through the warm, but cooler air
above it. This creates gusts know as both shinokes and Santa Anna Winds.
Precipitation:
The heat from the sun will heat up water, which evaporates. Now the water is a
vapor, and therefore logically it will join the air movement as discussed previously.
However, when water vapor cools down and becomes more dense, unlike air it will
not simply sink and replace the warmer air below it, rather it will solidify back into
a liquid state. We call this condensation. Warm air will start to condese water vapor,
and thus clouds will form and move across the sky. However the colder the water
vapor becomes, the harder it becomes for the cloud to remain in the atmosphere. In
a sense warm air can hold more moisture than cold air, so the colder the air, the
more likely the cloud will break apart creating precipitation. As the rain droplets fall
to the ground, if they pass through even hotter air, they will re-evaporate in midair
and create humidity, which will eventually rise, form new clouds and repeat itself,
however, if the air is cool enough it will fall all the way to the surface, and thus rain
is the result. If it passes through freezing temperatures it will freeze into snow
flakes. If it rapidly moves from warm to freezing just before hitting the surface it can
freeze into ice pellets. The dew point means that the air at that temperature is fully
saturated with as much water as it can hold. When this water condenses it forms
fog, clouds, or precipitation based on the atmospheric conditions and temperature.
Weather Patterns(Putting It All Together):
Stability. If an air mass is stable, it will resist vertical movement. An unstable air
mass will allow sparatic movement, which causes shifts in wind, turbulence, and
potential thunderstorms and other hazardous weather.
There are two basic clouds Cumulus and Stratus:
Cumulus clouds are round and puffy, associated with unstable air, wind, and
showery precipitation. I.E unstable air.
Stratus clouds are flat and rigid, and are associated with stable smooth air, steady
continuous precipitation, I.E. stable air.
High Clouds
Middle Clouds(Alto)
Low Clouds
Cirrus
Nimbo/Nimbus is associated with rain.
Front:
A front is the boundary layer between two different types of air mass. This is
because two large air masses with different characteristics usually don’t mix well, so
there will be discontinuities between the two. One may over take the other, but
there will more or less be changes in-between the boundary layers.
Cold air overtaking warm air is a cold front and vice versa. If the cold air is dry and
stable stratus clouds form. However, if the cold air is moist and unstable cumulus
clouds form and if the front is moving fast enough it can create a thunderstorm. A
line of thunderstorms ahead of the front boundary is called a squall line. A slow
moving front is less sever. Since it is slow the slope will not form as violent weather.
Occlusion is where one air mass overtakes another and then a different air mass
overtakes the first one. Warm occlusion is where cold air is overtaken by warm air,
and then cooler air overtakes the warm air, but this air is still warmer than the
original cold air. A cold air occlusion is when cool air is overtaken by warm air, and
then colder air overtake both the cool and warm air.
Thunderstorms:
Cumulus-Some Lifting Action
Mature-Rain drops at the surface
Dissipating- Downdrafts
Rising air lifts moisture higher, and higher, until it can push it up anymore. Once the
cloud becomes so saturated and the rising air cannot lift the rain the rain will fall to
the surface. This rain will carry wind with it, and create downdrafts, and eventually
the storm will shift from continuous updrafts, all the way to downdrafts. When these
downdrafts hit the surface they will spread out and blow side to side, creating gusty
winds, and potential windshear. Maintain at least 20 miles lateral distance, and do
not fly above or below them.
If a thunderstorm(s) are inadvertently encountered, a constant attitude should be
maintained but there will be variations in airspeed and altitude, and perhaps
significant ones, do to all of the extreme winds patterns.
Turbulence:
Microburst: Sometimes occur in verga, and may be indicated by trees blowing in
different directions when a thunderstorm is in the vicinity.
They can cause…….and last as long as …….
Mountains, cause turbulence when air is stable and as it hits the mountain it
becomes wavy.
Wake turbulence is caused by larger aircraft. Vortices of wind are generated by the
wing tips of larger airplanes and move downward. Wake turbulence will decrease
after a few minutes.
Weather Services:
Be careful not to think that because the weather is nice in the vicinity it will be nice
across the entire route of flight. Also, remember weather can and does change
rapidly.