Meteorology/Everyday Weather

General Info
Everday weather is what some would consider the most complex subject for Meteorology, mainly because it covers all bases of Meteorology, even some climate and storm systems. but the major information to learn will  include:
 * Structure and composition of the modern atmosphere
 * Properties of water
 * Types of clouds associated with weather
 * Heat transport including the energy budget, insolation, albedo, convection and radiation
 * Atmospheric circulation including the Coriolis Effect, planetary wind belts, jet stream, local wind patterns (including Chinook winds, mountain and sea breezes) and the three cell model of circulation
 * The origin, temperature, density, moisture content and stability of air masses
 * Fronts
 * Surface weather stations
 * satellite imagery, isobars, isotherms, surface weather maps showing isobars, fronts, and radar data; metograms; Doppler imagery
 * Weather instrumentation including barometers, thermometers, anemometers, sling psychrometers, rain gauges, radiosondes, rawinsondes, and the Beaufort scale
 * Atmospheric phenomena

Everyday Weather focuses on the mechanics of Earth�s atmosphere and how it causes daily weather. This is a large shift from Climate that emphasizes long-term predictable patterns of weather

Origins of the atmosphere
this may seem like a review to some of you but still read it you may learn something new

The origin of Earth�s atmosphere is subject to  debate. We can be fairly certain of is that when the Earth was formed around five billion years ago, it was too hot to retain the gases that it had in its primordial atmosphere. Earth�s first atmosphere most likely consisted of helium, hydrogen, ammonia and methane.

What happened over thousands of years is that volcanoes emitted amounts of water vapor, carbon dioxide and nitrogen- the same gases emitted by volcanoes today. This expulsion of gases from Earth�s interior is a process known as outgassing. The water vapor expelled by the hot, volcanic Earth in turn created clouds, which produced rain.

Over time, the rain would accumulate in basins as rivers, lakes and oceans. These basins in turn acted as sinks for accumulated carbon dioxide, which later became locked into deposits of limestone and other sedimentary rocks. Nitrogen, which is not chemically active, accumulated in the atmosphere. Any significant amounts of oxygen probably did not exist in Earth�s early atmosphere.

Only when tiny bacteria living in Earth�s oceans developed the ability to split water molecules apart by using the energy of sunlight could any significant amount of oxygen begin to accumulate in the atmosphere. it was these prossess that are Believed to have produced the modern atmospheric composition of 78% nitrogen and 21% oxygen.

Organization
The atmospheric layer are in order from sea level to space:

Troposphere
The troposphere is where all weather takes place. It is a region of rising and falling pockets of air moving mostly vertical.

Stratosphere
The stratosphere is located above the troposphere. it has a large concentration of ozone. You�ve probably flown up into the lower levels of the stratosphere above the clouds on an airplane. The skies are always clear in the stratosphere because you are above the level that clouds can form. Unlike the troposphere, airflow in the stratosphere is mostly horizontal.

The stratosphere contains the ozone layer which absorbs the majority of the dangerous radiation from the sun

Mesosphere
Above the stratosphere is the mesosphere. In the mesosphere, temperatures drop with increasing altitude

Thermosphere
outer most layer

you should know how the temperature changes within each layer

Earth Energy Budget
The Earth�s Energy Budget is determined by the amount of incoming energy and the amount of outgoing energy. Nearly all of Earth�s incoming energy (99.98%) is from solar radiation. About .013% comes from geothermal energy that is created by the radioactive decay of Earth�s core. About .002% of Earth�s incoming energy comes from the action of tides caused by the interaction of Earth with the Sun and Moon. Waste heat energy from fossil fuel consumption accounts for about .007% of Earth�s Energy Budget. The Earth has an average albedo of about 30% which means that ~30% of incoming solar radiation is radiated back into space before it reaches Earth's surface. After the 30% the atmosphere absorbs 19% and the earths surface absorbs 51%

Around 70% of solar energy that is absorbed by the Earth is reradiated as infrared energy. The Earth�s Energy Budget is in equilibrium as the amount of incoming energy is balanced by the same amount of outgoing energy.



Convection
Convection is the transfer of heat from the Earth�s surface into the atmosphere. When a layer of air receives enough heat, it expands and is pushed upward by buoyancy. Then air becomes denser and moves laterally until it begins to sink and then begins to rise again as it warms. Atmospheric convection currents may cause breezes, winds, cyclones and thunderstorms.



Radiation Budget
Radiation budget refers to the balance between incoming radiation from the Sun and the outgoing thermal, or longwave and reflected shortwave energy from Earth. Globally the budget is balanced as the amount of incoming solar radiation is transformed into latent heat, or even kinetic energy. Energy transfers in the oceans along with the atmosphere keep the radiation budget in balance

But locally the Radiation Budget is unbalanced because tropical regions retain more insolation, while less is retained in higher latitudes.This accounts for differences in the temperature and pressure of air masses that originate in both regions affecting weather throughout the planet

Air Masses and Winds
Air Masses-Large bodies of air
 * Move and affect large areas

Classifications

 * Classified by the nature anf surface in the source region
 * Continental (c) form over land normally dry
 * Maritime(m) form over Water normally humid
 * Classified by Latitude of source region
 * Polar(P) at high latitude;cold
 * Tropical (T) low latitude;warm
 * Types
 * cP:Continental Polar
 * cT:Continental Tropical
 * mP: Maritime Polar
 * mT: Maritime Tropical
 * Air masses and weather
 * cP and mT are the most important air masses in the Norther rockie
 * Continental Polar
 * cP(continental Polar) originates in Northern Canada and interior Alaska where the winter brings frigid dry air and summer brings cool weather.
 * cP is responsible for lake effect snow due to the cP crossing the great lakes; air picks up moisture from lakes and snow on the leeward shoe of the lakes
 * Maritime Tropical
 * mT(maritime tropical)originates in the Gulf of mexico and also the Atlantic Ocean.Warm moist air brings precipitation to the U.S
 * Maritime Polar
 * mP(Maritime Polar)Originates over water in polar regions
 * mP brings precipitations to Western mountains

Planetary Winds
Global scale winds are winds that are created in the different Global circulation Cells.

you have the:
 * 1) Polar Easterlies
 * 2) Prevailing Westerlies
 * 3) Trade Winds

The polar easterlies blow from the Pole to 600

The Prevailing Westerlies blow from 600 to 30 0

The Trade Winds blow from 300 to00

Mountain/valley winds
During the day, mountains warm, causing the air over them to be warmer than the air over the valley at the same elevation. Warming the air causes it to rise up, creating a valley wind. During the evening, the air cools due to a loss of surface energy to space. The cool dense air moves down slope as a mountain wind.

Chinook winds
A Chinook wind is a warm dry wind on the leeward side of a mountain. As air descends the leeward side of a mountain, it is compressed and adiabatically heated. Warming the air causes the saturation point to increase, causing a decrease in its relative humidity. The new warm and dry wind moves down slope rapidly, and during the Spring causes substantial melting of mountain snow.

Santa Ana winds
Santa Ana winds are warm and dry winds. Over plateau regions in the desert region of the United States, high pressure pushes the air off the plateaus, forcing the air into narrow mountain valleys. As the air is forced through the valley it compresses and warms. As the air warms the saturation point rises and its relative humidity drops.

Fronts

 * Fronts
 * Fronts are narrow boundaries that separated air masses
 * some mixing occurs but air masses mainly retain their identities
 * Warmer,less dense air is forced aloft
 * Colder,more dense air acts like a wedge and pushes pushes wait air up

Types
Five Types
 * 1) Stationary Front
 * 2) Cold Front
 * 3) Warm Front
 * 4) Occluded Front
 * 5) Dry Line

Warm front
 * Shown on a map as semicircles
 * warm air replaces cool air
 * clouds become lower as front nears
 * Slow rate of advance
 * light to moderate precipitation
 * gradual temp increase

Cold Front
 * shown on map as triangles
 * cold air replaces warm air
 * weather is more violent than warm front
 * faster rate of advance
 * precipitation intense
 * clear after front passes

Stationary Front
 * air flow parrelel on both sides
 * doesn't move
 * widespread clouds
 * Precipitation light

Occluded Fronts
 * active cold front overtakes a warm front
 * weather is complex
 * precipitation associated with warm air

Water in the Atmosphere
The atmosphere of our planet is laden with water. In temperate and tropical regions, water exists mainly in liquid form. In the poles and higher latitudes, much of Earth�s water exists as ice locked away in alpine or continental glaciers. The physical composition of Earth�s atmosphere consists primarily of water vapor.

Humidity refers to the amount of water vapor that is in the air. This water vapor exists in a gaseous state. The process in which water changes from a liquid into a gaseous state is evaporation. Each water molecule that becomes water vapor also takes with it a parcel of heat energy from the surface it evaporates from cooling the surface(evaporative cooling). Evaporative cooling explains why you may feel a chill after swimming as water evaporates off the surface of your skin, taking with it heat from your body.

During the spring when the amount of daylight is increasing and the declination of the hemisphere is tilting towards the Sun, the intensity of solar radiation increases causing ice crystals in the upper troposphere to melt and fall as rain. As the water is exposed to increased solar radiation it evaporates and returns to the atmosphere in a gaseous state- as water vapor. The humidity of the atmosphere increases as spring changes to summer.

To measure water vapor we would use an instrument known as a hygrometer. Measurements of humidity are often expressed as a percentage, which is termed relative humidity. The Complete saturation of the air (100% relative humidity) occurs when the amount of water vapor in the air equals the amount of water vapor that the air can hold.

Precipitation
Any form of water that falls to earth the major ones are
 * rain
 * snow
 * sleet
 * hail

Liquid Precipitation
Mist consists of droplets less than .05mm in diameter. Drizzle is anything larger than.05mm but less than .5mm larger than 0.5mm across is rain. Most raindrops are not larger than 5mm across because of air drag effects that would tear larger droplets into smaller droplets as they descended through the air.

Frozen Precipitation
Snowflakes fall as ice crystals and have diameters of between 1mm and 2cm.

Graupel is around 5mm fall as soft and mushy ice

Sleet is similar to graupel, but it is smaller really nothing more than frozen raindrops.

Hail is larger than 5mm and is a rounded clump of hard ice and is usually associated with thunderstorms

Another variation is rime a deposit of ice that freezes out of the air onto a surface that has a temperature below 0�C.

Virga
precipitation that falls from clouds- but never reaches the surface of the Earth. This is termed virga.

At high altitudes, precipitation falls mainly as ice crystals before they melt and evaporate before reaching the ground because of compressional heating that occurs as a result of increasing air pressure closer to the ground (remember- air that is compressed becomes warmer).

Streams of falling precipitation that never reach the ground make the clouds appear to have commas attached to them as aloft winds push the bottom ends of the virga into angles. Virgas can be hazardous to pilots because the pockets of extremely cold air descending from the upper atmosphere can create microbursts.

Formation of clouds
Clouds are nothing more than small droplets of water and ice crystals that clump together within the atmosphere. They may produce precipitation in the form of liquid water and/or ice crystals that fall to the Earth�s surface. Rising air is an important process in the formation of clouds. As air rises, it expands causing it to lose heat energy and voila the temperature of the air decreases. The water vapor molecules that are in the air also increase the humidity of the air until it is saturated (100% relative humidity).

Excess water vapor condenses changing from a gas into a liquid on large aerosol particles in the atmosphere if the relative humidity is not in excess of 100%. When the atmosphere cools, it will reach the point at which the air is saturated with water vapor and can precipitate.This is the dew point. The dew point is defined as the temperature to which a particle of air would need to be cooled in order to reach this point of saturation. The air�s capacity to hold water vapor is temperature dependent. Warmer air tends to hold more moisture, while cooler air holds less.

The dew point and relative humidity can be measured using a psychrometer, a weather measurement tool consisting of two identical thermometers mounted side by side. One of the thermometers- the dry bulb measures air temperature. The other thermometer- the wet bulb- has a damp wick wrapped around it allowing it to measure any decrease in temperature. This indicates the maximum amount of cooling that can result from evaporation.

To use a psychrometer, it needs to be exposed to a flow of air by slinging it around on a handle. The humidity of the air is directly proportional to the amount of moisture evaporating off the wet bulb. If the two thermometers have identical readings, than no evaporation has taken place and the air is saturated with water vapor. The more significant the measured difference between the two thermometers, the drier the air and the lower the level of humidity.

Cloud formation is closely related to the cooling of humid air masses. As water vapor expands- it cools in temperature. Likewise, when air is compressed- it heats up. This change in temperature caused by the expansion or contraction of gases is known as adiabatic temperature change. This is a cooling or warming of the air caused by expansion or contraction and not by the increase or irradiation of heat.

The effects of adiabatic temperature change in Earth�s atmosphere can be dramatic. Air sinking down from higher latitudes is warmed by an increase in atmospheric pressure as it contracts. Likewise, warm air that climbs in altitude is under less pressure and cools as it expands. When this air is enriched in water vapor and cooled down to its dew point, condensation and cloud formation can take place.

Cloud ID
For the event you need to be able to identify clouds and weather that come with each cloud. Cloud prefixes tell you where the clouds are located.

"cirr-", like cirrus clouds, can be located at high levels

"alto-", like altostratus, can be found at middle levels

Cloud types are classifies by height of the ground these are three of the classifications This is a list identifying which clouds go in which layer. I found these from "The cloud book: how to understand the skies" by Richard Hamblyn
 * Upper Clouds
 * 9000 meters
 * Cirus clouds
 * Intermediate Clouds
 * 3000-7000 meters
 * Altocumulus
 * Lower Clouds
 * 2000 meters
 * Nimbostratus
 * High Fogs
 * Under 1000 meters
 * 1) Low Clouds
 * 2) Stratocumulus
 * 3) Stratus
 * 4) Cumulus
 * 5) Cumulonimbus
 * 6) Medium Clouds
 * 7) Altocumulus
 * 8) Altostratus
 * 9) Nimbostratus
 * 10) High clouds
 * 11) Cirrus
 * 12) Cirrocumulus
 * 13) Cirrostratus

Clouds
Great Cloud page http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/cld/cldtyp/home.rxml

Great Cloud book is "The cloud book: how to understand the skies" by Richard Hamblyn



Forcasting
There are many ways to forecast, but the simplest way is to take today's weather and say that tomorrow is going to be the same. This can be called the Persistence method.

The next method can be called the trends method. It relies on mathematics to get the forecast. This method involves being able to get a accurate measerment of the speed at which the weather system is moving and plugging the numbers into the speed formula (S=d/t) and determining the time at which the system will be at your position.

The next method can be called the trends method it relies on mathematics to  forecast. This method involves being able to get a accurate measerment of the speed at which the weather system is moving and putting the numbers into(S=d/t) and determining the time at which the system will be at your position Here is an example of the trend model:

The Climatology Method is another easy way of forecasting. This method involves averaging weather statistics accumulated over many years to make a forecast.

The Analog Method is a more complicated method of producing a forecast. It involves examining today's forecast scenario and remembering a day in the past when the weather scenario looked very similar. Than you would predict that the weather in this forecast will behave similar to the day in the past.

Phenomena
There are many weather phenomena here they are the major ones

How To read weather maps/satellite imagery
We are going to start off with the very basic weather map the kind that you will most likely see at competition:
 * 1) Start by identifying the different pressure zones on the map. Above it is already done but if it wasn't marked look for sections that have a circle with a very high or low pressure.
 * 2) Look for fronts. This can be done by looking at the station ball symbols. (those are the yellow circles with the tails the tails indicate wind direction) look and find a sudden change in wind direction/pressure that will normally indicate a front. I marked where I believe a front to be.

There are many lines on this map. Each one means something:
 * The blue lines are isobars which mean that they are lines of constant pressure.
 * The yellow circles with "tails" are called station ball symbols of station models; they are explained in the next section.

Something else you might see on a weather map is a isotherm, which is a line of constant temperature.

Station Models


This image is a station model. It can tell you many different things, like wind speed, wind direction, temperature, dew point, current weather, cloud cover, and pressure, given that you know how to read and interpret it. Some symbols have more information than others on them, but here is a basic overview:


 * The 48 is the current temperature
 * The 45 is the dew point
 * The "whatever" that is in between the two numbers is the current weather. On this one it is a light rain.



This is what tells you information about the wind. The direction the stick faces shows the wind direction, and how many lines on the end of it show the wind speed. A half line signifies five knots, a full line ten knots, and a bold line 50 knots.



This indicates how much cloud cover there is. There are nine choices:

Map Symbols
this is from here:http://www.sover.net/~redcamp/wxplegend.gif

METAR
This is a way that meteorologists convey what is happening at a point on Earth. It is a very abbreviated language. Here is an example of METAR:

KCLL 312253Z 14007G15KT 10SM CLR 31/15 A2990 RMK AO2 SLP120 T03110150

all of this means something, you just have to know what the abbreviations mean.

Zulu is a time measurement based off of a 24-hour clock

here is a more in depth METAR guide: http://www.met.tamu.edu/class/metar/quick-metar.html

Terms To Know
Some basic terms

Links
This is a great meteorology site and some of the images on this page have come from it: http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/home.rxml