Met2 Flashcards
Layers of the tropopause
MBL, PBL, Troposphere above surface layer
Molecular Boundary Layer (MBL)
extends up from the Earth’s surface to approximately one centimeter (about .4 inch) The MBL is the transition layer between the Earth’s surface and the Troposphere.
Planetary Boundary Layer (PBL)
begins at the top of the MBL then extends upward to the gradient level. The layer’s thickness is about 1km or 2,000 to 3,000 feet above the surface. Other names for the PBL are the surface layer or friction layer.
The gradient level
the uppermost edge of frictional effects. In other words, it is the level of the atmosphere where surface friction does not affect wind direction or speed.
Troposphere above surface layer
This is the largest layer. extending from the gradient level to the tropopause. Its average thickness is 35,000 to 40,000 feet.
three groups of permanent gases that essentially remain constant
Nitrogen (78%), Oxygen (21%), and the remaining 1% which includes Argon, Neon, Helium, Hydrogen, and Xenon.
variable gases
Variable gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone.the most important variable gas is water vapor. Its greatest concentration is in the troposphere, where its amount varies between 0 and 4% based on atmospheric temperature
Both warm and cold air can hold a maximum of
4% water vapor. Warm air has a higher capacity than cold air
How is Air and water similar?
They both have depth, width, and they move in currents. the only differences are air is less dense and more compressible than water.
How is the physical composition of air evaluated?
by using two methods or perspectives. One is in a column of air and the other is an individual air parcel.
Atmospheric pressure
the weight of the atmosphere exerted on Earth due to gravity
Density
the amount of mass in a column of air. Its formula is ρ = m/V. density changes in the atmosphere are due to changes in mass and volume.
Density relationship with mass and volume
If mass increases in a column, then density increases and if mass decreases in a column, then density decreases. Second, density is inversely proportional to volume when mass is constant. This means when the height of a column of air increases its density decreases and when the height of the column of air decreases its density increases.
Parcel pressure
the amount of force applied to a specific area on an air parcel
Formula for force
P = F/A where P is pressure, F is force, and A is area.
Force
In our atmosphere, air parcels exert force to the atmosphere while the atmosphere exerts force to air parcels.
Atmospheric heating
the transfer of energy into the atmosphere
Weins law
an emitter’s temperature determines the radiation’s wavelength and hot emitters such as the Sun emits radiation with short wavelengths.
Wavelength
the distance from trough to trough or from crest to crest
Scattering
Insolation is scattered when it strikes objects in the atmosphere meaning it can deflect in all directions instead of reaching the Earth. In fact, 30% is scattered, 6% by the atmosphere, 20% by clouds, and 4% by the Earth’s surface.
Reflection scattering
returns to space on the same trajectory as its approach.
Rayleigh scattering
occurs when insolation strikes objects smaller than its wavelength such as individual molecules, fine dust, or pollutants. When it happens with a low sun angle, yellow, orange, and red, wavelengths are scattered creating red sunsets and sunrises.
Mie scattering
occurs when insolation strikes objects larger than its wavelength such as an air parcel, clouds, or the ozone layer. Insolation filters through the object and continues moving toward the Earth’s surface.
Absorption
The atmosphere absorbs 19% of insolation. There are two types of radiation absorbed by the atmosphere. First, ozone and oxygen absorb ultraviolet radiation. Second is infrared radiated absorbed by water vapor and carbon dioxide. The Earth absorbs 51% of all types of radiation emitted by the Sun.
Kirchhoff’s law
every absorber is also an emitter
Greenhouse Effect
The Earth absorbs short-wave insolation then it emits long-wave eradiation into the atmosphere. Water vapor and carbon dioxide in the atmosphere absorbs the eradiation.
Atmospheric Temperature
it was found that the standard atmospheric temperature for the Earth’s surface is 15°C (59°F), the tropopause is near -60°C, and the troposphere cools at a standard lapse rate of negative 6.5°C per kilometer (km)
First Law.
An object in motion remains in motion or an object at rest remains at rest until acted on by an external force.
Second Law
The force on an object is equal to it mass times its acceleration.
Third Law
For every action, there is an equal and opposite reaction
Contour gradient force (CGF).
initiates winds above the surface It is measured perpendicular to the contours, which are lines of equal height
Pressure gradient force (PGF)
Pressure gradient force initiates surface winds. It is measured perpendicular to isobars, which are lines of equal pressure. Everything else works exactly like CGF.
Gradient force (contour and pressure)
determines wind speed. When gradient force increases, wind speeds also increase. The opposite is also true when gradient force weakens wind speeds will decrease.
Coriolis force
an apparent force opposing gradient force It is directly related to gradient force meaning when gradient force increases, Coriolis force also increases and vice versa. It deflects air parcels to their right changing wind direction, but not wind speed.
Centripetal force
(petals, flowers) (come together.) only present when air parcels move through curved flow It pulls air parcels toward the center of a curve and the amount of force is strictly dependent on the orientation of the curved flow. If the radius increases, CeP force weakens and curvature decreases. Conversely, if the radius decreases, CeP force strengthens and curvature increases.
Centrifugal force
(FU) (get away) only present when air parcels move through curved flow.It opposes CeP force meaning it pulls air parcels away from the center of the curve. Its relationship to curved flow is the same as CeP force.
Frictional force
opposes parcel movement. it only exists between the Earth’s surface and the gradient level. The thing to remember is increasing terrain, moving from a valley into mountains, increases friction. When friction increases wind direction will back counterclockwise (e.g., south to east) and the wind speed decreases. Decreasing terrain does the opposite. Wind direction will veer clockwise (e.g., south to west) and the wind speed increases.
Momentum
Momentum is the tendency of air parcels to remain in uniform motion meaning their direction and speed does not change. Air parcels moving in a straight line have linear momentum while air parcels moving in curved flow have angular momentum. Momentum can change from linear to angular and vice versa enabling the atmosphere to conserve momentum
Buys Ballot’s Law
if you stand with the winds to your back lower pressure or lower heights are always to your left and higher pressure or higher heights is always to your right.
Counterclockwise flow
cyclonic circulation associated with low pressure or low height centers. The forces in balance are contour gradient and centripetal forces equal to Coriolis and centrifugal force
Clockwise flow
anticyclonic circulation associated with high pressure or high height centers. The forces in balance are Coriolis and centripetal forces equal to contour gradient and centrifugal forces
Straight-line flow
When gradient force is stronger than Coriolis force, air parcels spin cyclonically to conserve momentum. They change their direction to their left and the winds become more cyclonic.
Cyclonic Circulation
When gradient and/or centripetal forces are stronger than Coriolis and centrifugal forces, parcels increase their cyclonic spin, their direction changes to the left, and wind flow becomes more cyclonic
Anticyclonic Circulation
When Coriolis and/or centripetal forces are stronger than gradient and/or centrifugal forces, parcels increase their anticyclonic spin, their direction changes to the right, and wind flow becomes more anticyclonic
Vorticity
the rotational effects of spinning parcels
Shear Vorticity
Shear vorticity is a change in wind speed over distance. It occurs when lower wind speeds surround an area of higher wind speeds
positive shear vorticity
Air parcels have a cyclonic spin indicating upward vertical motion. Positive vorticity occurs on the left side of the strongest winds.
zero shear vorticity
Air parcels have no spin, all forces are in balance, and there is no vertical motion. This only occurs along the axis of the strongest wind speeds.
negative shear vorticity
Air parcels spin anticyclonically indicating downward vertical motion. They occur on the right side of the strongest winds.
Curvature Vorticity
Curvature vorticity is a change in wind direction over time and it is always present in curved flow
Positive curvature vorticity
in cyclonic flow with cyclonically spinning air parcels indicating upward vertical motion.
Zero curvature vorticity
occurs in straight-line flow between cyclonic and anticyclonic flow. In other words, zero curvature vorticity is at the inflection point where air parcels do not spin and there is no vertical motion.
Negative curvature vorticity
occurs in anticyclonic flow. Air parcels have anticyclonic spin, which indicates downward vertical motion
Relative Vorticity
Relative vorticity is the combination of shear and curvature vorticities. It measures the actual strength of weather systems relative to curved or straight-line flow
Convergence
occurs when wind from two different directions merge This creates an excess of mass and energy at the level of convergence resulting in vertical motion. Upward vertical motion forms above the level of convergence and downward vertical motion is below the level of convergence.
Divergence
when a single wind separates into two different directions.It creates a void in the atmosphere that must be filled so upward vertical motion forms below the level of divergence and downward vertical motion takes place above the level of divergence.
Chimney & Damper Effect
The “chimney effect” forms when surface convergence is directly below divergence in the upper atmosphere. The overall effect is upward vertical motion between the surface and the troposphere.
Conversely the “damper effect” forms when upper-level convergence is directly above surface divergence. This results in downward vertical motion through the troposphere.
