Terms in this set (257)
The "innermost layer", creates solar radiation through nuclear burning.
the "middle layer" of the Sun's interior, resembles dense mass of gold.
"third layer" of the Sun's interior, lies directly under the Sun's surface and is approximately 200,000 km thick.
primarily responsible for the nuclear reactions within the Sun, those processes which produce the heating we receive on Earth.
the "inner layer", a thin layer, a few 1000 km thick, at a temperature of about 10,000 K.
has a very irregular shape, with increasing temperatures as we look from the inner most edge (5,700 degree Celsius) to the outermost edge (2,000,000 degree Celsius).
Outermost layer, 1,000,000 km thick, at a temperature of about 1,000,000 K.
the visible surface of the Sun. It is approximately 100 km thick, with an average temperature of 5,700 degree Celsius.
Filaments and/or Prominences
Cooler than photosphere. They are dark, thread-like features in the chromosphere or dense, cooler clouds above the photosphere.
are regions of warmer temperatures within the chromosphere. They appear as bright regions of intensely localized magnetic fields.
are low temperature regions in the photosphere. They are about 4000 K (2000 K cooler than solar surface) and have magnetic fields up 1000 the normal solar magnetic field.
are dark regions within the corona, which are often found at the Sun's Poles.
Interplanetary Magnetic Field
is a spiral-shaped magnetic field which emanates from the Sun's magnetic Poles.
defined by the amount of detectible sunspots, varies from year to year.
is characterized by a 4 year rapid rise to solar maximum, followed by a 7 year gradual decline to solar minimum.
During this time, the Sun's magnetic field is distorted and space weather impacts all operations.
During this time, other features are mostly non-existent and the magnetic field is not distorted. There are relatively fewer space weather impacts during this time frame.
the Earth is closest to the Sun on January 3rd with the distance of 91 million miles.
farthest from the Sun on July 4th when it is approximately 95 million miles away
is an apple-shaped magnetic field that is closest to the Earth at the magnetic Poles and farthest from Earth over the magnetic Equator.
will always face the Sun, and it creates a bow shock.
faces away from the Sun and has a sword-like appearance.
layer of electrons in the Earth's atmosphere that has four sub-layers that range from 30-250 miles.
consists of a continuous outflow of solar energy which is emitted in all directions by the interplanetary magnetic field.
are nuclear explosions which occur on the Sun's surface.
consist of and are characterized by rapid variations in the Earth's magnetic field.
occur when solar energy reaches the ionosphere, occurring 24 to 72 hours after a solar flare, in response to a geomagnetic storm.
Sudden Ionospheric Disturbances (SID)
are fluctuations in the degree of incoming solar radiation; more specifically the X-ray or extreme ultraviolet spectrums.
results from rapid changes in particle ionization. These events occur when charged particles enter the ionosphere and collide with atoms.
referred to as the "Northern Lights" and occurs in the higher latitudes of the northern hemisphere
referred to as the "Southern Lights."
June 21st, the Sun is directly over the Tropic of Cancer, which is located at 23.5 degrees North. This results in longer days than nights in the northern hemisphere.
December 21, the Sun is directly over the Tropic of Capricorn, which lies at 23.5 degrees south. This results in longer nights for the northern hemisphere.
September 22, the Sun crosses the Equator in a southward direction. This results in equal amounts of solar energy for both the northern and the southern hemispheres; days and nights are equal in duration.
March 20, when the Sun is once again directly over the Equator; days and nights are of equal duration in both hemispheres.
first layer of the Earth's atmosphere contains what we refer to as weather-producing meteorological features, including clouds, precipitation, obstructions to vision, tornados, and other atmospheric phenomena.
second layer of the Earth's atmosphere; contains the ozone layer, which absorbs incoming ultraviolet radiation and acts as the primary heat source for the stratosphere.
the third layer of the Earth's atmosphere that contains the Aurora.
fourth atmospheric layer. It extends from the mesopause up to the exobase and contains the greatest number of electrically charged molecules in the atmosphere.
final layer of the Earth's atmosphere. The temperature here cools with height, allowing atoms and molecules to escape into outer space.
the study of the Earth's oceans.
are cyclic rises and falls of seawater, which are influenced heavily by the Moon and the Sun.
Tide that will occur when the earth is parallel on the Moon
Tide that will occur when the earth is perpendicular on the Moon
occur when the Sun and the Moon are parallel to Earth. This occurs every 14 to 15 days, during New Moon and 3-10
There is one high and one low diurnal tide per tide day.
occur when the Sun and the Moon are perpendicular to Earth, every 14 to 15 days, during first quarter Moon and last quarter Moon.
consist of two high and two low tides per tide day. This occur along the United States east coast and in Europe.
have differing individual tide heights; meaning that one high tide is higher than the other and one low tide is higher than the other.
is a polar high, made up of a continental arctic air mass, which forms slightly poleward of the Arctic jet.
The Arctic high is associated with _____________.
is a subpolar low which forms between the Arctic and Polar front jets. During the winter months, the center is located near the western edge of the Aleutian chain. In the summer, the center may be found in the Gulf of Alaska.
The Aleutian low is associated with _____________.
is a subpolar low which forms between the Arctic and Polar front jets. Its center is located between Maine and Greenland during the winter months, but moves near Iceland during the summer.
The Icelandic low is associated with _________.
is a subtropical high consisting of a maritime tropical air mass. It forms between the Polar front and Subtropical jets and is a warm core system.
hot and humid weather
The Pacific high is associated with _____________.
This high is a subtropical high which consists of a maritime tropical air mass. It forms between the Polar front and Subtropical jets and is a warm core system.
hot and humid weather
The Bermuda-Azores high is associated with ________.
the transition zone, or boundary, between two air masses.
is defined as the leading edge of an advancing cold air mass. It is drawn as a solid blue line with blue triangular pips. The pips indicate the direction the front is moving.
is the leading edge of an advancing warm air mass. It is drawn as a solid red line with red semi-circle pips, which also indicate the direction of movement.
is a stalled boundary between two air masses. The red pips point poleward on the red line and the blue pips point equatorward on the blue line.
occurs when a cold front moves faster than a warm front and overtakes it.
is a large body of air with similar temperature and moisture characteristics.
air masses form over land areas. It is characterized by a lowercase "c" which indicates dry air.
air masses form over large open ocean areas. They are designated by a lowercase "m" which indicates moist air.
air masses form in frigid climates, they are found closest to the poles.
Even though the name "polar" denotes high latitudes, the temperatures must be very cold for a strong air mass to form.
air masses form in very warm climates.
warm, moist air
hot, dry air
cool, moist air
cold, dry air
frigid, dry air
United States Geological Survey (USGS)
manages a vast network of ground-based magnetometers which are designed to measure the strength and direction of the Earth's magnetic field.
Air Force Weather Agency (AFWA)
primary point of contact for space weather as a whole and obtains data from the USGS, observes and analyzes solar activity, forecasts solar events, and finally, issues warnings for adverse space weather events; such as geomagnetic storms or ionospheric storms.
World Meteorological Organization (WMO)
is an intergovernmental organization established in 1950 and is the agency of the UN for weather, climate, hydrology, and geophysical sciences.
South West Pacific region (Region V)
the Philippines belonging to the __________________ in WMO.
Routine/SA (hourly obs)
scheduled wx observation, as well as the name for the code used. Taken and transmitted at the end of every hour (55 to 59), even if the weather is identical to the last METAR
SPECI/SP (Special Weather Report)
Unscheduled obs taken (in addition to METARs) when special criteria are observed.
Horizontal motion of air past a given point.
is always rounded to the nearest 10 degrees azimuth with reference to true north
Change in wind direction by 45° or more in less than 15 minutes with sustained winds > 10 knots throughout the wind shift
Rate of movement of air past a given point over 2 minutes
Max wind speed over a 10-minute period, indicated by rapid fluctuations with a variation of > 10 knots between peak and lull
Peak Wind Speed
The highest (maximum) instantaneous wind speed observed or recorded; reported on hourly obs if speeds exceed 25 knots
Strong wind characterized by a sudden onset in which the wind speed increases by at least 16 knots and is sustained at 22 knots or more for at least 1 minute
Greatest visibility equaled or exceeded throughout at least half of the horizon circle, not necessarily continuous.
greatest horizontal distance at which selected objects can be seen and identified
Visibility in a specific direction, representing a 45° arc (or more) of the horizon
Variable prevailing visibility
Condition where the prevailing visibility is < 3 miles (4800 meters) and rapidly increasing and/or decreasing by 1/2 mile (0800 meters) or more during the observation period
Report when surface and/or tower visibility is < 4 miles and differs by a reportable value from the surface visibility
Runway visual range (RVR)
Instrumentally derived value (10 min avg) representing the horizontal distance pilots can see down the runway
Water particles, liquid or solid, that fall from the atmosphere and reach the ground
Fairly uniform precipitation composed of fine drops with diameters of less than 0.02" (0.5 mm) that are very close together
The first is in the form of drops
larger than 0.02" (0.5mm). The second can have smaller drops, but unlike drizzle, they are widely separated
Solid form of precipitation which contains crystals, most of which are branched in the form of six-pointed stars
Snow grains (SG)
Very small, white opaque grains of ice. Don't bounce or shatter when they hithard ground. Never showery.
Ice crystals (IC) (diamond dust)
Unbranched ice crystals in the
form of needles, columns,
or plates. Glitters in sunshine
or bright lights
Ice pellets (PL) (formerly sleet)
Transparent/translucent frozen rain drops (0.2"/5mm or less)Bounce/make sound on impact. Falls continuous or intermittent
Snow pellets (GS)
2nd type of Ice Pellets Consists of white, opaque grains of ice Brittle, easily crushed, break on landing. Falls as showers
Clear or opaque layers of ice. May be individual or frozen together
Any atmospheric phenomenon (excluding precipitation) that reduces horizontal visibility to less than 7 miles (exception: volcanic ash)
Minute water particles suspended in the atmosphere reducing visibility to < 7 miles but > 5/8 mile
Minute water particles suspended in the atmosphere reducing visibility to < 5/8 mile
Small suspended particles produced by combustion.
Suspended dry particles invisible to the naked eye, but sufficiently numerous to give it an opalescent appearance
Volcanic Ash (VA)
Fine particles of rock powder erupted from a volcano and remain suspended in the atmosphere for long periods of time
Widespread Dust (DU)
Fine particles of earth or other matter raised or suspended in
the air by the wind that may have
occurred at or away from the unit
Sand particles raised to a sufficient height that reduces visibility
An ensemble of water droplets torn by the wind from the surface of a large body of water, generally from the crest of waves, and carried a short distance into the air
Dust/Sand Whirl (PO)
Commonly known as Dust Devils. Whirling column of dust or sand with varying height, small diameter, with an approximate vertical axis
air column touching the ground
Funnel cloud (FC)
violent, rotating air column not touching the ground
air column that forms (or moves)
over a body of water and touches
the water surface
Sand particles carried aloft by strong wind. Particles mostly confined to
lowest 10ft and rarely rise above 50ft
Severe weather condition
characterized by strong winds over an extensive area
Entire sky without physical obstruction
Visible accumulation of minute water droplets or ice particles in the atmosphere above the surface
Clouds or obscuring phenomena with bases at approximately the same level
Amount of sky hidden by clouds and/or obscuring phenomena
Clear (CLR automated / manual)
Absence of clouds or obscuring phenomena
3/8 through 4/8
5/8 through < 8/8
Condition where SFC-based phenomena (i.e., fog) hides 8/8 of the sky
is the vertical visibility into a surface based total obscuration which hides the entire celestial dome.
Vertical Visibility (VV)
is the distance one can see upward into a total obscuration.
Condition where SFC-based phenomena hides at least 1/8 but <8/8 of the sky
is the height above the Earth's surface of the lowest broken or overcast layer
Measure of the average kinetic energy of air molecules
Temperature a given parcel of air must be cooled at constant pressure and constant water vapor content for saturation to occur
Ratio, expressed as a percentage, of actual vapor pressure of air to saturation vapor pressure
by the atmosphere at a given point
Pressure measured by a barometer
Atmospheric pressure at station elevation (Hp) - what your barometer really reads
Sea Level Pressure
Pressure value obtained by theoretical reduction of station pressure to sea level
is a broad, elongated area of lower pressure that migrates between 10° North (N) and 10° South (S) with the seasons. It is formed by the chimney effect between the tradewinds.
is a series of thermal lows commonly found over land areas during the summer months. It is responsible for most thunderstorm activity over land in the tropics.
Near Equatorial Tradewind Convergence (NETWC)
is an east to west line of convection over the oceans between 5°N and 10°N.
is a disruption of the ocean-atmosphere system in the tropical Pacific Ocean.
forms when the tradewinds decrease speed and are unable to push water towards the western Pacific Ocean.
cyclonic circulations of lower pressure
01 June through 30 November
Tropical cyclone season in the northern hemisphere officially lasts from ____________.
poleward of 5°N
Tropical cyclone form in _____________ order for Coriolis to induce circulation.
Stage of TC:
Slight wind circulation
Not a closed circulation
Stage of TC:
Closed cyclonic circulation
Sustained surface winds: 20 to 33 knots
Storm assigned a number
Stage of TC:
Well-defined cyclonic circulation
Sustained surface winds: 34 to 63 knots
Storm given a name
Hurricane or Typhoon
Stage of TC:
Well-developed cyclonic circulation
Eye in center with average diameter of 5 to 20 miles and calm winds
Surface winds 64 knots or greater
Designated super hurricane or super typhoon if winds are 130 knots or more
- A monsoonal wind system is one that changes direction seasonally, blowing from one direction in the summer and from the opposite direction in the winter.
Southwest monsoon (Summer monsoon)
In summer, there is a seasonal reversal of the wind flow pattern, as intense surface heating, creates a low-pressure system over the Tibetan Plateau.
Northeast monsoon (Winter monsoon)
During the winter, extremely cold air forms high pressure over Siberia. This strong high pressure extends to the Tibetan Plateau, creating anticyclonic winds over the Asian continent.
This is the upward vertical motion of air resulting strictly from density differences within the atmosphere.
This is the upward vertical motion of air resulting from outside forces. This "mechanical" force can come in a variety of forms; frontal lift forces warm, moist air up and over a cooler, denser air mass.
The first stage of thunderstorm development is the cumulus stage. During this stage, the storm consists of updrafts only and precipitation forms aloft. The updraft keeps precipitation from falling to the surface.
During the mature stage, both updrafts and downdrafts are present. Precipitation becomes too heavy to remain aloft and falls towards the surface creating downdrafts.
During the dissipating stage, the storm consists of downdrafts only.
is an electrical discharge. The upper part of the cloud produces a positive charge, while the lower portion produces a negative charge. The earth's surface is positively charged.
is an audible shock wave.
thunderstorms form in mountainous regions. This development is due to forced convection (mechanical lift).
thunderstorms form in lines and are much more violent compared to air mass thunderstorms.
When the outflow boundaries from neighboring thunderstorms interact with each other, the low level convergence between these outflow boundaries often develop new thunderstorms.
Mesoscale Convective Complexes (MCCs)
This storm system forms in a circular pattern with a diameter near 200 miles. The initial thunderstorms form from free convection and can become severe with increased divergence aloft.
Mesoscale Convective System (MCS)
This is a large, elongated area of thunderstorms and is usually associated with fronts or troughs. Every thunderstorm with this system has the potential to be severe; development continues until the divergence aloft decreases.
Supercell severe storms
is an enormous thunderstorm with updrafts balanced so that it is able to maintain itself as a single entity for hours on end. This type of storm produces tornadoes and destructive hail.
Sea or lake breeze
During the day, the land heats up more quickly than the adjacent water; the warmer air over the land rises; resulting in a shallow thermal low over the land.
At night, the land cools more quickly than the water. The air above the land becomes cooler than the air above the water, producing just the opposite effect of a sea breeze.
is a daytime phenomenon that develops in the morning hours and reaches peak strength during the afternoon. The sun heats up the slopes of the mountains causing the air above the slopes to rise.
At night the mountain slopes cool off quickly as does the air above them. This air then sinks towards the valley resulting in a gentle down slope breeze. This tertiary wind develops just after sunset and reaches peak strength prior to sunrise.
are rapidly rotating columns that have contact with the earth's surface. The vortex is only considered a tornado when it touches the ground. Otherwise it is referred to as a funnel cloud.
is a vortex that forms over water. This feature does not require the same dynamics as a tornado.
takes place in a cloud of supercooled water droplets and will typically form in one of three methods:
1. The deposition of water vapor on some type of particulate matter
2. Water vapor condensing and later freezing
3. Contact between supercooled water droplets or two supercooled water droplets colliding
Single Trip Theory
occurs as the hailstone ascends along on the edge of the updraft.
Multiple Trip Theory
The hail is "recycled" between the updraft and forward flank downdraft, melting and refreezing, becoming bigger with every trip.
is normally a convective process caused by thunderstorms, but it may also occur during non-convective events.
the air temperature and temperature of the water droplet must be 0°C or less. Supercooled water droplets commonly exist in temperatures ranging from 0°C to -22°C.
-16°C to -22°C It occurs when these small cloud droplets hit the wing and freeze immediately before having time to spread out.
0°C to -8°C As the large supercooled droplets strike the leading edge of the wing, they spread out and form a layer of water that slowly freezes into a solid sheet of ice.
-9°C to -15°C There are situations where both types of icing exist. When this occurs, it is termed mixed icing. This may occur in occluded systems where both stratiform and cumuliform clouds are present.
are warm, dry winds that commonly occur on the eastern slopes of the Rockies. In the Alps, this wind is referred to as a foehn wind, and in Argentina, a zonda.
a cold, dry wind with many similarities to a chinook wind. In the Alps, this wind is referred to as a mistral wind.
Thunderstorm outflow boundary
is a boundary separating thunderstorm cooled air from the surrounding air; similar in effect to a cold front where passage is marked by a wind shift and usually a drop in temperature.
is a small downburst which can extend up to 2 ½ miles from the center of the storm.
is a large downburst which can extend up to 5 miles from the center of the storm.
Law of Inertia
states that every object in a state of uniform motion tends to remain in that state unless an external force is applied to it.
states that the relationship of an object's mass, acceleration, and applied force is F = ma.
Newton's 3rd law of Motion
states that for every action there is an equal and opposite reaction.
refers to the process by which large droplets absorb the mass and acceleration of smaller droplets.
BUYS BALLOT'S LAW
states that in the Northern Hemisphere with the wind at your back, low pressure, and lower heights, will be to your left.
When a parcel sinks from the upper atmosphere down to the surface, friction increases, the speed decreases and the wind direction backs; counter-clockwise (turn left).
When a parcel increases altitude from the surface to the upper atmosphere, friction decreases, speed increases and the wind direction veers clockwise (turn right).
Coriolis force (CoF)
is caused by the Earth's rotation, or it at least appears that way. When we talk about forces acting on a parcel, or any other meteorological situation, we use geographic locations as our frame of reference.
Contour gradient force
similar to pressure gradient force in that, it too initiates the winds. The difference comes from the fact that this force initiates the winds in the upper air.
Pressure gradient force
This force initiates the winds on the surface. This causes the wind to blow from higher to lower pressure.
Centripetal force (CeP)
The process increases parcel pressure inward to the center of the curve. The amount of centripetal force is strictly reliant on the amount of curvature within the flow.
Centrifugal force (CeF)
This is an apparent force that deflects winds outward from the center of rotation. This force, just as with centripetal force, only exists in curved flow and opposes centripetal force (CeP).
is the tendency of mass to remain in uniform motion.
momentum in straight-line flow.
momentum in a curved flow and therefore takes into account the radius of rotation.
are a mathematically derived representation of atmospheric flow meant to resemble observed data.
contour gradient force and Coriolis force must equal each other. This means when air parcels move up and around a ridge Coriolis force must remain constant when the contour gradient is held constant.
Geostrophic wind (Vg)
exist when a parcel's speed is able to maintain its height above the Earth's surface. The geostrophic wind blows exactly parallel to isobars because the CGF or PGF exactly balance the CoF.
Super-geostrophic wind (Va).
occur with poleward moving parcels and are always observed at the apex of a ridge.
Sub-geostrophic wind (Vc)
conditions occur with equatorward moving parcels and are always observed at the base of a trough.
winds are a mathematically derived representation of atmospheric flow meant to correct geostrophic winds in curved flow.
They are most commonly found ahead of a jet maximum and upstream of a ridge axis
characterized by parcels moving from a tighter gradient to a weaker gradient. They are most commonly found ahead of a jet maximum and upstream of a ridge axis.
They are most commonly found behind a jet maximum and upstream of a trough axis.
refers to the horizontal movement of air.
warm air advection (WAA)
If warmer air moves into a given area
cold air advection (CAA)
If colder air moves into a given region
occurs when wind from two different directions merge together, forcing a collision of parcels within a given region.
occurs when a single wind separates into two different directions. This process creates a void in the atmosphere.
Upward vertical motion that creates convergence near the surface and divergence in the upper atmosphere.
Downward vertical motion and a result of upper level convergence and low level divergence.
extends from the North Pole to the Arctic Circle. This cell creates a damper effect at the North Pole, which results in downward vertical motions (convergence aloft and divergence at the surface).
This process develops the polar easterlies, with an average surface temperature of 0° C.
results from the chimney effect at the Arctic Circle. A portion of this upper atmospheric flow continues equatorward, creating a damper effect at the Tropic of Cancer.
results from the damper effect at the Tropic of Cancer. Essentially, the northeast trade winds continue until reaching the Equator, where a chimney effect develops.
are strong horizontal winds concentrated in narrow bands.
is the center of the strong winds. In other words it is the center of the jet stream.
is quite simply an intermittent region of stronger winds along the jet axis
Arctic jet (AJ)
associated with the polar tropospheric leaf and forms due to horizontal temperature contrast.
Arctic jet (AJ)
The _______________ has the lowest altitude and the warmest temperatures of the four.
Polar front jet (PFJ)
located at the intersection of polar and mid-latitude tropospheric leafs.
Polar front jet (PFJ)
The __________ varies in altitude and temperature more widely than the other three.
Subtropical jet (STJ)
located at the intersection of the mid-latitude and tropical tropospheric leafs.
Subtropical jet (STJ)
The _______________ has the highest altitude of the four jets and the coldest temperature.
Tropical Easterly Jet (TEJ)
flows from east to west in a zonal pattern. It forming over the Arabian Sea and extending beyond the western coast of Africa.
Tropical Easterly Jet (TEJ)
The importance of the _______________ is that it provides energy for tropical wave development.
Chemical composition of air: Nitrogen ________
Chemical composition of air: Oxygen ____________
Chemical composition of air: Others (Argon, Neon, Helium, Hydrogen, and Xenon)
process that considered to be a "reversible" process.
warm air rises to higher heights. Parcels rise at varying rates. The parcel cools, reaches saturation and clouds form.
The original parcel begins to sink to lower heights due to its colder temperature and increased density. The parcel returns to the surface regaining its original temperature and its dew point returns to its original value.
process that is considered to be an "irreversible process."
occurs when cloud droplets collide.
occurs when larger water droplets ingest smaller droplets.
defined as the transfer of energy into the atmosphere.
is quite simply incoming solar radiation. The Sun emits short-wave radiation in waves according to Wein's Law.
states that an emitter's temperature determines the radiation's wavelength.
The amount of insolation received by our atmosphere depends on three factors.
How much radiation that the Earth receives?
Of that 30%, how much radiation is deflected by clouds?
Of that 30%, how much radiation is deflected by the atmosphere?
Of that 30%, how much radiation is deflected by the Earth's surface?
This creates our blue sky.
occurs when radiation strikes objects larger than its wavelength such as an air parcel, clouds, or the ozone layer.
the radiation returns to space on the same trajectory as its approach.
Eradiation - Earth radiation
energy radiated from the Earth.
It tells us that every absorber is also an emitter.
It occurs when eradiation is absorbed by water vapor and carbon dioxide in the atmosphere. This energy is reradiated to the Earth and warms the boundary layers.
is the energy transfer by direct molecular contact. It always transfers energy from warmer molecules to colder molecules.
refers to the transfer of energy resulting from changes in density. It begins when parcels are heated through another heating process such as insolation/eradiation (Earth radiation).