Basic Equations of Atmospheric Motion - Lecture 2

Question 1

Eulerian view/derivative

Answer 1

consider changes at a fixed point in the fluid
Eulerian derivative: rate of change at a fixed point
∂/∂t

Question 2

Lagrangian view/derivative

Answer 2

consider changes as you follow a particle (or parcel) of fluid
Lagrangian (or material) derivative: rate of change moving with a fluid parcel
D/Dt

Question 3

v

Answer 3

v is the 3-dimensional velocity vector (u,v,w)

Question 4

ρ [rho]

Answer 4

density=mass/volume

Question 5

Coriolis force

Answer 5

f(k X v)

acts at right angles to the velocity

Because the Earth rotates on its axis, circulating air is deflected toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere.

Question 6

P.g.f

Answer 6

pressure gradient force (p.g.f.) goes from high to low pressure
(1/density) *(grad pressure)
the rate at which the pressure increases divided by the density

Question 7

g

Answer 7

gravity

Question 8

F (Capitalised)

Answer 8

friction acts in opposite direction to velocity

Question 9

f (lower case)

Answer 9

Coriolis parameter
f = 2Ω sin φ with Ω rate of Earth’s rotation ≈ 7.3x10-5 rad s-1 and φ is the latitude (north is positive)

Question 10

k

Answer 10

vertical unit vector

Question 11

p

Answer 11

pressure

Question 12

hydrostatic balance

Answer 12

p.g.f=force of gravity

Question 13

geostrophic balance/flow

Answer 13

p.g.f=Coriolis
the resulting geostrophic flow/wind/fluid is parallel to the isobars

Question 14

isobars

Answer 14

lines on weather map that join places of equal pressure
-think level set

Question 15

θ

Answer 15

potential temperature
usually θ=T(p/1000)^(2/7)
*the exponent is the Poisson constant

Question 16

T

Answer 16

temperature

Question 17

R

Answer 17

R is the specific gas constant (e.g. for dry air R = 287 J kg^–1 K^–1)

Question 18

adiabatic

Answer 18

heat does not enter or leave the system