Studied by 39 people
Looks like no one added any tags here yet for you.
Meteorology
The study of atmospheric phenomenon (its meaning has changed over time, and the ancient Greek meaning of meteor was “high in the air”)
The different types of atmospheric “meteors”
clouds, raindrops, snowflakes, fog, dust, and rainbows
Examples of Hydrometeors
the primary types of cloud droplets and forms of precipitation that contain water in any phase
Lithometeor examples
smoke, haze, dust, and other condensation nuclei
Electrometeors
Visible or audible manifestations of atmospheric electricity (for ex. thunder and lightning)
Weather
The current state of the atmosphere, when we speak of weather, we are referring mainly to short-term variations in the atmosphere.
Climate
Long-term variations in weather (usually over the course of 30 yrs or more)
How is radiation from the sun distributed around the planet?
At high latitudes, the Sun’s rays hit Earth at angle, and near the equator the Sun’s rays hit nearly straight on (due to Earth’s tilt, nights are longer and colder).
Why are the tropics warmer than the poles?
The Sun’s rays are more spread out when they strike Earth at a low angle, and the solar radiation reaching the Earth’s surface at the poles is therefore less intense. (currents also influence weather on land).
Why don’t the tropics become steadily warmer if the Sun is always directly overhead? How do regions manage to maintain fairly constant average temperatures?
The tropics and other places maintain fairly constant average temperatures because heat energy is redistributed around the world.
Motion of air and water balance
The continual motion of air and water reallocates heat energy among Earth’;s surface, oceans, and atmosphere and brings it into balance. Virtually everything that we consider to be weather is part of this constant redistribution of Earth’s heat energy.
Air mass
A large body of air that takes on the characteristics of the area over which it forms, and they form over land or water. (the region over which an air mass forms is called the source region). The air masses that form over land have less exposure to large amounts of moisture, so they are drier than those that form over water (air masses take on the temp of the source region as well). Warm air masses form over tropics, cold ones form over currents.
Info about different air masses
Arctic cA has a cold and dry airmass. In winter, cP air masses are cold. MT air masses are hot and moist, CT air masses are hot and dry.
Where can the five main types of air masses be found?
All can be found in North America because the continent’s proximity to the source regions associated with each air mass.
Are air masses stationary?
No, they’re not. They move, transferring heat from one area to another and thus establishing the heat balance discussed earlier. They may travel over land or water - and will acquire some of the characteristics of the new surface beneath it. When this happens, it is said to undergo air mass modification. Wind moves the air masses.
Air mass modification
the exchange of heat or moisture with he surface over which an air mass travels.
Summary of Air mass features
cA: very cold, dry, very stable, and very low tropopause height, MA: cold, moist, unstable in lower levels, and a low tropopause height. cP: cold, dry, fairly stable, and low tropopause height, MP: cool, moist, unstable, and medium tropopause height. MT: hot, moist, very unstable, and high tropopause height, cT: very hot, dry very unstable, and very high tropopause height.
What would happen if Earth were either all land or all water and didn’t rotate on its axis?
A large convection cell would form in each hemisphere with the colder and denser air at the poles sinking to the surface and flowing toward the tropics. There, it would force the warm air already at the equator to rise, and then it would cool and flow back toward the poles.
Coriolis Effect
As Earth rotates, the Coriolis Effect turns winds in the Northern Hemisphere toward the right, it causes hurricanes (they move counter-clockwise in northern hemp, opposite in southern hemp). The effect combines with the heat imbalance found on Earth to create distinct global wind systems that transport colder air to warmer areas and warmer air to colder areas (reseulting in the balance of heat energy).
The three basic zones/wind systems
Trade winds, prevailing westerlies, and the polar easterlies.
Trade Winds
They occur at 30 degrees north and south latitude. There, air sinks, warms, and moves toward the equator in a westerly direction. When the air reaches the equator, it rises again and moves back toward latitude 30 degrees, where it sinks and the process starts anew. The sinking air creates a belt of high pressure - causing generally weak surface winds.
Horse Latitudes
At 30 degrees North and South little wind here so they would throw the horses over board.
Prevailing westerlies (NOT REALLY BEING TESTED ON THIS*)
Flows between 30 degrees and 60 degrees north and south latitude in a circulation pattern opposite that of the trade winds. In this zone, surface winds move toward the poles in a genereally easterly direction.
Polar easterlies
They lie between 60 degrees north-south latitude, and at the poles. (east to west).
What is Earth’s weather strongly influenced by?
Atmospheric conditions and events that occur at the boundaries between wind zones. On either sides of these imaginary boundaries, both surface and upper level air differs greatly in temp and pressure (high temp=low pressure). Wind, pressure, and temp are related, adn wind goes from areas of high pressure (cooler temp) to low pressure.
How is wind caused?
By differences in temp and pressure. Therefore, a large temp gradient in upper-level air should result ins strong westerly winds, and this is what happens. Narrow bands. of fast, high-altitude, westerly winds called jet streams flow at speeds up to 115 m/hr. All weather is influenced by a jetstream - normally weather goes south-north or west-east. The polar jet stream separates the polar easterlies from the westerlies, and the subtropical jet is located where the trade winds meet the westerlies.
What other consequences do tghe different pressure and temps pf aor masses have?
In the middle latitudes, air amsses with different characteristics sometiems collide, forming a front.
Front
Region separating two air masses w diff densities. Front is formed when teh two diff air masses collide. They can stretch over thousands of km across Earth’s surface, and the interactions between teh colliding masses can bring dramatic changes in weather.
Cold Front
When cold air moves under warm air, which is less dense, and pushes the warm air up (symbolised with a string of blue triangles). Frequent rain with possible thunderstorms, cooler temp and dryer air after front passes.
Warm Front
When hot air pushes against the cold air (depicted by a string of red ovals/circles). Light rain, and humid temps.
Stationary Front
Air masses on either side of the boundary are not moving, or are barely moving (depicted by a string of blue triangles and red ovals/circles). Cloudy, and overcast with light showers, conditions do not change until another system passes through.
Occluded Front
When a warm front is overtaken by a cold front (depicted by a string of purple triangles and circles/ovals). Severe snowstorms.
What is the atmosphere’s gas composition?
Air is a combo of gases, such as nitrogen + oxygen and particles, such as dust, water droplets, and ice crystals. CO2 makes up under 1% of the atmosphere, Ozone (O3) is a gas formed by the addition of a third oxygen atom to an oxygen molecule (O2). CO2, O3 and water vapor are important in regulating the amount of energy the atmosphere absorbs. (evidence that the ozone layer is thinning).
What’s the amount of atmospheric water vapor?
Amount of atmospheric water vapor ranges from 4% of the atmosphere down to almost zero.
What are the different layers of the atmosphere from closest-farthest from us?
Troposphere, stratosphere, mesosphere, thermosphere, and the exosphere (ozone layer lies in the stratosphere). Each layer differs in composition and temperature.
Does Earth’s atmosphere contain atmospheric particles?
Yes, Earth’s atmosphere contains variable amounts of solids in the form of tiny particles, such as dust, salt, and ice.
Troposphere Info
The troposphere, the layer closest to Earth’s surface, contains most of the mass of the atmosphere, including water vapor.
Most weather takes place in and most air pollution collects in the troposphere.
The troposphere is characterized by a general decrease in temp from bottom to top.
The upper limit of the troposphere, called the tropopause, varies in height.
Stratosphere info
The stratosphere, which is above the tropopause, is a layer made up primarily of concentrated ozone.
The stratosphere is heated because ozone absorbs ultraviolet radiation, and air gradually increases in temp to the top of the layer, called the stratopause.
Mesosphere/thermosphere info
The mesosphere is the atmospheric layer above the stratopause.
The top boundary of this layer is the mesopause.
The thermosphere is the atmospheric layer above the mesopause that contains only a minute portion of the atmosphere’s mass.
Ionosphere/exosphere info
The ionosphere, which is made up of electrically charged particles and layers of progressively lighter gases, is part of the thermosphere.
The exosphere, which is composed of light gases such as helium and hydrogen, is the outermost layer of Earth’s atmosphere.
There is no clear boundary between the atmosphere and space.
What are the solar fundamentals?
The Sun is the source of all energy in the atmosphere.
This energy is transferred to Earth and throughout the atmosphere through radiation, conduction, and convection.
The Sun is shining on, and therefore warming, some portion of Earth’s surface at all times.
While Earth is absorbing solar radiation, it is also continuously sending energy back into space.
What is radiation?
Radiation is the transfer of energy through space by visible light, ultraviolet radiation,a nd other forms of electromagnetic waves.
Radiation info
The rate of absorption for any particular area varies depending on the physical characteristics of the area and the amount of solar radiation it receives.
Most of the solar radiation that travels through the atmosphere does so at short wavelengths, which are not easily absorbed.
Earth’s surface absorbs the solar radiation and then radiates energy with longer wavelengths, which warm the atmosphere through conduction and convection.
What is conduction?
Conduction is the transfer of energy that occurs when molecules collide.
Conduction info
Through conduction, energy is transferred from the particles of air near Earth’s surface to the particles of air in the lowest layer of the atmosphere.
For conduction to occur, substances must be in contact with one another.
Conduction affects only a very thin atmospheric layer near Earth’s surface.
Convection info (definition alr stated above)
Pockets of air near Earth’s surface are heated, become less dense than the surrounding air, and rise.
As the warm air rises, it expands and starts to cool.
When it cools below the temperature of the surrounding air, it increases in density and sinks.
Convection currents are among the main mechanisms responsible for the vertical motions of air, which in turn cause different types of weather.
Why is ozone important?
Ozone absorbs ultraviolet radiation from the sun. If ozone did not control the amount of ultraviolet radiation reaching Earth’s surface, our skin could not tolerate exposure to the Sun for very long.
Temp vs Heat
Temp is a measurement of how rapidly or slowly molecules move around.
Heat is the transfer of energy that occurs because of a difference in temp between substances.
Heat is the transfer of energy that fuels atmospheric processes, while temperature is used to measure and interpret that energy.
How do u measure temp?
Temp can be measured in degrees Fahrenheit, degrees Celsius, or in kelvins, the SI unit of temp.
The Kelvin scale measures the number of kelvins above absolute zero, a point where molecular motion theoretically stops.
What is the dew point?
The dew point is the temp to which air must be cooled at constant pressure to reach saturation.
Saturation is the point at which the air holds as much water vapor as it possibly can.
Condensation cannot occur until air is saturated.
When does condensation occur?
Condensation occurs when matter changes state from a gas to a liquid.
Vertical temp changes
The temperature of the lower atmosphere decreases with increasing distance from
Earth’s surface.
An air mass will cool off by 10°C for every 1000m increase in altitude to dry adiabatic lapse rate
If the air is able to continue rising, eventually it will cool to its condensation temperature.
The lifted condensation level, or LCL, is the height at which condensation occurs.
The moist adiabatic lapse rate is the rate saturated air cools at
4°C/1000 m in very warm air
9°C/1000 m in very cold air.
Air pressure and density info
The atmosphere is held onto the Earth by gravity.
Air pressure increases as you near the bottom of the atmosphere because of the greater mass of the atmosphere above you.
Atmospheric pressure decreases with height because there are less gas particles on top of you.
The density of air is proportional to the number of particles of air occupying a particular space.
Wind info
Air moves by the unequal heating and cooling of Earth’s surface.
These imbalances, in turn, create areas of high and low pressure.
Wind is air moving from an area of high pressure to an area of low pressure.
Wind speed usually increases with height because there is less friction.
What is convergence?
Convergence - air forced upward by colliding winds and creates an area of low pressure.
Near the equator, convergence occurs over a large area called the intertropical convergence zone (ITCZ).
The ITCZ migrates south and north of the
equator as the seasons change (i.e. where the suns rays strike at 90°).
The ITCZ appears as a band of cloudiness and occasional showers.
What causes climates?
Latitude
Topography
Closeness of lakes and oceans
availability of moisture/humidity
global wind patterns
ocean currents
air masses
Latitude info
The amount of solar radiation received by any one place varies because Earth is tilted on its axis, and this affects how the Sun’s rays strike Earth’s surface.
Topographic Effects/ What is a rain shadow
A rain shadow is an area of land (mountain range) that receives reduced precipitation due to proximity to mountain ranges. The mountains block the passage of rain-producing weather systems, casting a "shadow" of dryness behind them. (winward is side that gets rain, leeward doesn’t)
The condition exists because as warm moist air rises through "orographic lifting" to the top of a mountain range or large mountain, it expands and cools to the point that the air reaches its dew point. At the dew point, moisture condenses onto the mountain and it precipitates precipitation onto the windward side and atop the mountain.
The air descends on the leeward side, and due to the process of precipitation has lost much of its initial moisture.
Descending air typically gets warmer in the process on the leeward side of the mountain, creating an arid region.
What’s the Koeppen classification system?
The Koeppen classification system is a climate classifications system that looks at:
Temp
Precipitation
Distinct vegetation found in diff climates.
A good way to distinguish different climatic zones is by natural vegetation.
Included the numerical values of temperature and precipitation for a more scientific approach.
Koeppen 6 climate zones
Tropical - Constant high temperatures (tropic of capricorn to cancer)
Dry – largest zone where cT air dominates (american south west)
precipitation low & vegetation scarce. (drought)
evaporation rates > precipitation rates
Mild – hot & muggy summers, cold & dry winters
Continental - clashing tropical and polar air masses. (more in the interior of U.S., forming tornadoes).
extreme summer and winter temperatures.
5. & 6. Polar & High elevation – Brutally Cold
Found at poles and high elevations
Avg. Temps < 10°F
What are microclimates?
A microclimate is a localized climate that differs from the main regional climate. (occurs in places that are really urbanized).
concrete and asphalt can create heat islands, where the climate is warmer than surrounding rural areas.
What is climactic change(s)?
During the av. human lifetime, climates do not appear to change significantly.
Climactic change is:
Natural
constantly ongoing
usually occurs over extremely long time periods.
What are ice ages?
Periods where average global temps decreased by about 5 degrees Celsius and there was extensive glacial coverage.
warm periods between ice ages → interglacial intervals.
the most recent ice age ended only about 10k yrs ago
Short-Term Climactic Changes info
The Seasons
When the north pole is pointed toward the sun, the northern hemisphere experiences summer and the southern hemisphere experiences winter.
El Niño
warm water from the western Pacific surges eastward toward the South American coast. (Hawaii to the Americas, and causes more/less rain)
develops about every 5 yrs
causes many short term climactic chnages
El Niño Effects
Tends to create stormy weather to areas that are normally dry and drought conditions to areas that are normally wet. (and also affects winds).
The strong upper winds help suppress hurricanes in the Atlantic Ocean.
What are the natural climactic changes?
solar activity
changes in Earth’s orbit
Changes in Earath’s axis tilt
Earth’s axis wobbles
Volcanic eruptions
Solar activity
The maunder minimum
a period of very low sunspot activity from 1645 to 1716
closely corresponds to an unusually cold climatic episode called the “Little Ice Age”
High solar activity(more sunspots) = warmer climatic conditions
Low solar activity (less sunspots) = cold climatic conditions.
Earth’s orbit
Elliptical Orbit
Earth passes closer to the Sun (closest when Northern Hemp is in winter)
temps become warmer than normal.
Circular Orbit
Earth is farther from Sun
temps dip below av.
Earth’s Tilt info
Earth’s tilt varies every 41k yrs (tilt at 23.5 degrees)
Changes in angle cause season to become more severe and may cause ice ages
Earth’s wobble info
Earth wobbles as it spins on its axis
By about the year 14k, the axis will be tilted in the opposite direction of today.
Seasons will be reversed.
our summer will be in December, Winter in June.
Volcanic activity climatic changes
some scientists theorize that high volcanic activity causes cool climatic periods.
Volcanic dust can remain in the atmosphere for several yrs.
Blocks incoming solar radiation (due to ash spewed into atmosphere)
