Atmo 251 Exam 2.0

What is a polar orbiter?

Orbits around the north and south poles, doesn't show one place the entire time (ex: ISS)

What is geostationary orbit?

When an object orbits at the same spot in relation to the earth (always shows the same place). If an object is far enough away, it will orbit at the same speed as the earth spins

What are wind profilers and what can they detect?

These are relatively low-power, highly sensitive, clear air radars (SODAR: radar or sound waves). They can detect changes in atmospheric density due to turbulent mixing of air

What wavelengths do wind profilers detect on?

33cm to 6m

What directions does i, j, k, u, v, and w correspond to?

i and u = x direction, j and v = y direction, k and w = z direction

What is vector subtraction important for determining?

Vertical wind shear (Shear is what keeps storms alive)

When expressed as a dot product, advection is greatest when…

Gradient is a large number, wind is a large number, wind is pointed in the same direction as the gradient, 2 vectors are parallel

What is the del operator?

Partial derivative that gives the gradient, can be taken in all directions

What is del h?

When looking at a plane, the horizontal derivatives of x and y

What is the advection equation with del?

-v*(del h T), T can be anything

What are the satellite types and what is their purpose?

Polar and geostationary, they get images and sounding data

What type of imaging is there?

Visible, infrared, water vapor, microwave

What are surface-based remote sensors?

Radar, wind profilers, and sounders

What wavelengths are used for a sounding?

Microwaves and infrared

What is the proportionality of radiation and temperature in relation to the Stefan Boltzmann equation?

Radiation is proportional to the temperature - as temp goes up, so does radiation

How is temperature determined using radiation?

Radiation leaves lower molecules headed for satellites; similar molecules higher up absorb the radiation; the higher molecules then emit a specific wavelength; the satellite receives the wavelength and then temperature can be determined

What is used to detect radiation and only allows certain wavelengths?

Filters in photomultiplier tubes, each filter is set to one specific wavelength

How can you find precipitable water?

By "condensing" all water vapor in an area to see how much rain you COULD get

What are the wavelengths for high in the troposphere, the middle of the troposphere, and the surface on satellites?

High = opaque, Middle = semi-transparent, Surface = transparent

What is the resolution of images?

4km but GOES is up to 1km resolution

What is a gradient?

Derivative in the horizontal

What is the wavelength and height water vapor can be detected at?

6.7 or 6.9 micrometers, easiest at 500+ mb (cannot detect low level water vapor

What is the wavelength of infrared images and what is the atmosphere?

Received 11-12 micrometers, the atmosphere is transparent

Visible image facts

Detects scattered/reflected radiation, high resolution, super detailed, only during the day

What is passive?

Tell is what is happening and what it is seeing, infrared and visible

What is active?

Emitting a "beam" and seeing what comes back, radar

What can doppler radar help determine?

The frequency/phase change because of movement

How can direction be determined with doppler radar?

Fat returning wavelengths and positive wind speed values means it is moving away

How are wind profiler signals emitted?

There is a "beam" sent straight up, 15N and 15E

What does VAD stand for and what is it used with?

Velocity azimuth display, it displays the wind profiler data with increasing time

What does a stratified atmosphere exhibit?

An increase of potential temperature with height

What does a well mixed atmosphere exhibit?

There's lots of vertical motion so there's a DALR and constant potential temperature with height

What is the horizontal advection equation?

-v * (del h T) = -u(dT/dx) - v(dT/dy)

How do you find 2D advection?

Components of the wind, gradient, the dot product or angular formula, (-|v| |del h T| cos(theta)

What is the cross products and how do you find it?

Represents a vector perpendicular to the plane, |a| |b| sin(theta)

What is relative vorticity?

Vertical component of vorticity that refers to the curl of horizontal wind

How do you calculate relative vorticity?

k * (del * v) = (dv/dx) - (du/dy)

What is vorticity?

Vector measurement of local rotation, del x v

What are plane polar coordinates?

They are used for circular motion with a radius. Theta from the x-axis radius is always positive, counterclockwise is positive angles

What coordinate system should be used for large scale things?

Spherical because it ignores the bulge at the equator

What is effective gravity?

The resultant of the centrifugal force and gravity

What is an isentrope?

A surface where potential temperature is constant

What is geopotential height (Z) and how is it expressed?

The height where an object would have the same geopotential as in the real atmosphere, Z = z(g/g0)

What is virtual temperature (Tv) and how do you calculate it?

The temperature if a parcel were to be given the same density and pressure as a moist parcel, Tv = T(1+.611w), w=mass vapor/mass dry air

What can critical thickness show?

The average temperature of a layer. Shows fronts with rapid changes, can vary with elevation and stability

For upper air maps, what is the spacing between isoheights?

12 decameters

What is the interval between isotachs?

20kt and you start at 50kt, shading begins at 70+ kt

For a surface map, what is the spacing between isobars?

4mb

What are ways to identify a front?

Sharp wind shifts, change in temperature, dew point contrasts, difference in thickness, troughs around lows

What are streamlines?

Lines that are drawn are parallel to the wind to show the overall wind field

What can streamlines show?

Fronts, convergence, divergence, and tropical weather

What is the final form of the hypsometric equation?

(Rd/g0) [ln(P1)-ln(P2)] Tv= Z2 - Z1