Wind & Air Pressure | Lecture 1

Speed, direction

The velocity of wind can be described by both TERM and TERM.

Acceleration is caused by unbalanced forces. When speed, direction, or both change, there is acceleration.

TERM is caused by unbalanced forces. When TERM, TERM, or both change, there is acceleration.

Direction, magnitude

For the purposes of this unit, there are two types of motion vectors: TERM, and TERM.

Pressure

Force per unit area

Units of pressure: N/m², hPa, mb

(Units of pressure: Unit, Unit, Unit).

barometer, decreases

Atmospheric pressure is measured by a TERM; it can vary greatly but generally atmospheric pressure TERMS exponentially with height.

surface pressure

(Term term) represents the weight of the air above the surface per square meter.

Change of pressure with height is much larger than changes of pressure horizontally— i.e topography. To account for altitude, surface pressure observations are corrected to sea level to reduce the strong dependence on height. Without such a correction, barometers would only measure elevation.

(Change of TERM with height is much TERMER than changes of pressure horizontally — i.e topography. To account for altitude, surface pressure observations are TERMED to sea level to reduce the strong dependence on TERM. Without such a correction, barometers would only measure TERM).

Closer to the surface, pressure is higher. Farther from the surface, pressure is lower. Topography makes land closer to/ farther from the surface. Thus, elevational variation corresponds to pressure variation — which is why a sea-level correction is required.

Closer to the surface, pressure is TERMER. Farther from the surface, pressure is TERMER. TERM makes land closer to / farther from the surface. Thus, elevational variation corresponds to pressure variation — which is why a sea-level TERM is required.

Isobars

Surface-level weather maps are contoured with lines of constant pressure called TERMS.

Cyclones

Low-pressure systems associated with instability and “Bad” weather

Anticyclones

High pressure systems associated with calm, “good” weather

ideal gas law

(Term term law) governs the relationship between pressure, density, and temperature.

Ideal gas law: p = (p)RT

P→ Pressure

(P) → density

R → Gas constant 287 Jkg^-1K^-1

T→ temperature

(Ideal gas law: p = (p)RT

P → TERM

(P) → TERM

R→ TERM TERM (#### Unit)

T → TERM (Unit)

When pressure is constant but temperature is changed

warming the air expands an air column

cooling the air compresses an air column

because of surface heating, air moves from high to low pressure

AIR COLUMNS ARE NOT AIR PARCELS

(When pressure is constant but temperature is TERMED,

Warming the air TERMS an air COLUMN

Cooling the air TERMS an air COLUMN

Because of surface heating, air moves from TERM to TERM pressure

AIR COLUMNS ARE TERM AIR PARCELS)

On ISOBARIC CHARTS, lines of constant pressure are used to measure height, and changes in height correspond with changes in pressure. On isobaric charts, pressure and height are directly proportional, where areas of low pressure correspond to areas of low height.

(On ISOBARIC CHARTS, lines of constant TERM are used to measure height, and changes in height correspond with changes in TERM. ON ISOBARIC CHARTS, Pressure and height are TERMLY proportional, where areas of TERM pressure correspond to areas of TERM height).

surface-level maps are maps of constant height that contour pressure with isobars

(surface-level maps are maps of constant TERM that contour TERM with TERMS)

upper-level maps are maps of constant pressure that contour height with isohypses

(upper-level maps are maps of constant TERM that contour TERM with TERMS)

meridional wind

A north-south wind observed on the mid-level 500mb map

zonal wind

A west-east wind observed on the mid-level 500mb map

pressure gradient force

change of pressure over a distance

PG = ^pressure / ^distance

Write pressure gradient force equation

Pressure gradients are larger for larger pressure changes over small distances and smaller for small pressure changes over large distances. The direction of the pressure gradient force is always perpendicular to isobars, and tightly packed isobars indicate larger force

(Pressure gradients are TERMER for larger pressure changes over small distances and TERMER for small pressure changes over large distances. The direction of the TERM TERM TERM is always perpendicular to isobars, and tightly packed terms indicate larger term)

coriolis force

An apparent force that acts on inhabitants of the earth’s surface due to the rotation of the earth that changes the direction of objects and fluids moving around the earth. It’s like a merry-go-round. If it’s not spinning, a ball thrown straight goes straight. If it is spinning, the ball goes in the direction of the spin.

If there is a flow, the Coriolis force moves it to the right in the Northern Hemisphere and to the left in the Southern Hemisphere

(If there is a flow, the Coriolis force moves it to the TERM in the Northern Hemisphere and to the TERM in the Southern Hemisphere).

The Coriolis Force is maximum at the poles, and it increases as flow approaches the poles. By contrast, the Coriolis Force is zero at the equator, and it decreases as flow approaches the equator.

(The Coriolis Force is TERM at the poles, and it TERMS as flow approaches the poles. By contrast, the Coriolis force is TERM at the equator, and it TERMS as flow approaches the equator.

The higher the latitude (i.e closer to the poles), the stronger the Coriolis force is

((The higher the latitude (i.e closer to the poles), the TERMER the Coriolis force is. ))

Speed and Coriolis force strength have a directly proportional relationship; higher speed corresponds to a stronger Coriolis force, and lower speed corresponds to a weaker Coriolis force

(Speed and Coriolis force strength have a TERMLY proportional relationship; higher speed corresponds to a TERMER Coriolis force, and lower speed corresponds to a TERMER Coriolis force. )

When an object isn’t moving, there is no Coriolis force.

(When an object isn’t moving, there is TERM Coriolis force).

Size is directly proportional to Coriolis force strength. Larger objects have a larger Coriolis force, and smaller objects have a smaller Coriolis force.

(Size is TERMLY proportional to Coriolis force strength. Larger objects have a TERMER Coriolis force, and smaller objects have a TERMER Coriolis force. )

Coriolis force only changes a moving object’s direction. It does not cause movement.

(Coriolis force only TERMS a moving object’s direction. It TERM TERM cause movement. )

The Coriolis force always acts at right angles to the wind speed. It changes direction, not speed.

(The Coriolis force always acts at term terms to the wind speed. It changes TERM, not TERM.)

Friction always acts against the direction of motion and decreases moving objects’ speed. It is most important near the surface due to surface roughness, where flatter or smoother surfaces like flat deserts produce less friction and rougher surfaces produce less friction

(Friction always acts TERM the direction of motion and TERMS moving objects’ speed. It is most important near the TERM due to TERM TERM, where flatter or smoother surfaces like flat deserts produce TERM friction and rougher surfaces produce TERM friction.)

centripetal force

The (Term term) is the force that governs change in direction for spinning/curved objects or flows. Inward directed force on a spinning object.

Centripetal force

The (Term term) is the force that governs change in direction for spinning/curved objects or flows. Outward directed force on a spinning object.

The centrifugal and centripetal forces are equal and opposite forces that govern spin or curved motion

((The centrifugal and centripetal forces are (term) and (term) forces that govern spin or curved motion))

Equation for Centrifugal force: Ce=V²/r
V— velocity
R— radius (how sharp the curve is)

Ce— centrifugal force

((Equation for Centrifugal force: Ce = V²/r
V— TERM

R—TERM (how TERM the curve is)

Ce— TERM TERM))

Gravity

Downward acting force

gravitational force: mg
Mass x acceleration of gravity
g=9.81m/s²

(Gravitational force: (letter)(letter)
TERM x TERM of gravity
(t) = #.##u/u^#)

PGF always flows from high to low pressure

((PGF always flows from TERM to TERM pressure.))

Coriolis force is always perpendicular to/at a right angle to wind movement

(Coriolis force is always TERM to / at a TERM TERM to wind movement.)

Friction requires movement, without it there is no friction.

(Friction requires TERM, without it there is TERM friction.)

In force balances, equal and opposite forces are acting on an object that “Cancel” each other’s effects

(In TERM TERMS, equal and opposite forces are acting on an object that “TERM” each other’s effects).

PGF, g

Which forces are in balance for the Hydrostatic Balance?

—Options (one or more)

PGF

g

Ce

CF

Fr

—

PGF, Ce

Which forces are in balance for the Cyclostrophic Balance?

—Options (one or more)

PGF

g

Ce

CF

Fr

—

PGF, CF

Which forces are in balance for the Geostrophic Balance?

—Options (one or more)

PGF

g

Ce

CF

Fr

—

PGF, CF, Ce

Which forces are almost in balance for the Gradient Wind?

—Options (one or more)

PGF

g

Ce

CF

Fr

—

PGF, CF, Fr

Which forces are in balance for the Surface Wind?

—Options (one or more)

PGF

g

Ce

CF

Fr

—

Hydrostatic balance, pressure gradient force, gravity, no

The (term balance) is a force balance of the upward force of the (TERM TERM TERM) and the downward force of (TERM). There is (TERM) up or down movement in this balance.

Cyclostrophic balance disregards the coriolis force because rotation is too small-scale and happens at too low of a latitude

(Cyclostrophic balance disregards the (term) force because rotation is too (term-term) and happens at too (Term) of a latitude).

In cyclostrophic balance, winds can rotate both clockwise (cyclonically) and counterclockwise (anticyclonically) but they must rotate around a low-pressure core to produce a force balance with the inward-moving PGF.

(In Cyclostrophic balance, winds can rotate (term) clockwise (termly) and counterclockwise (termly) but they must rotate around a (term-term term) to produce a (term term) with the (term)-moving PGF. ))

Geostrophic balance is the balance between the pressure gradient force and the coriolis force. it is associated with straight winds aloft, the forces of friction and centrifugal force are disregarded. The balance is created as PGF accelerates air from high to low pressure and the CF increases proportionally with the speed until the two forces equalize and produce constant motion, a steady state with no acceleration or net force. The flow of this air is parallel to the isobars with high pressure on the right.

(Geostrophic balance is the balance between the TERM TERM TERM and the TERM TERM. It is associated with TERM winds aloft, the forces of TERM and TERM force are disregarded. The balance is created as PGF accelerates air from TERM to TERM pressure and the CF increases proportionally with the speed until the two forces TERM and produce constant motion, a TERM state with no acceleration or net force. The flow of this air is TERM to the isobars with TERM pressure on the right).

A stronger PGF corresponds to a stronger geostrophic wind. The geostrophic wind is an idealized flow from a geostrophic balance between pressure gradient force and follows either isobars or height contours

(A stronger PGF corresponds to a TERM geostrophic wind. The geostrophic wind is an idealized flow from a TERM balance between TERM TERM TERM and follows either isobars or height contours).

The Gradient Wind is the approximate balance between pressure gradient force, coriolis force, and centrifugal force. It is known as balanced because of its constant speed parallel to curved isobars, yet it does have directional acceleration, though depending on the situation this acceleration can be negligible. The net force here is the centripetal force.

(The Gradient Wind is the approximate balance between TERM TERM TERM, TERM TERM, and TERM TERM. It is known as balanced because of its TERM speed parallel to curved isobars; yet it does have TERM acceleration, though depending on the situation this acceleration can be TERM. The net force here is the TERM force.)

Low-pressure cyclonic flows are called sub-geostrophic flows and are weaker than the flower of the geostrophic wind

(Low-pressure (anticyclonic/cyclonic) flows are called “term-term” flows and are termer than the flow of the geostrophic wind.)

High-pressure cyclonic flows are called super-geostrophic flows and are stronger than the flow of the geostrophic wind

(High-pressure (anticyclonic/cyclonic) flows are called “term-term” flows and are termer than the flow of the geostrophic wind.)

The surface wind is like the geostrophic wind, but it includes frictional effects. It is a balance between pressure gradient force, coriolis force, and friction. Friction slows the wind, reducing the coriolis force— a quantity dependent on the wind speed. This wind blows from high to low pressure across the isobars; more turning across the isobars occurs with rough surfaces, lower wind, and more proximity to the surface.

((The Surface Wind is like the geostrophic wind, but it includes (term) effects. It is a balance between TERM TERM TERM, TERM TERM, and TERM. Friction TERMS the wind, reducing the TERM TERM — a quantity dependent on the wind speed. This wind blows from TERM to TERM pressure across the isobars; more turning across the isobars occurs with TERM surfaces, TERM wind, and more TERM to the surface.))

convergence

When more air is entering an area than leaving. Air coming together at a location and being concentrated, creating violent vertical motion.

divergence

When more air is leaving an area than entering. Air moving away from a location and becoming diffused.

Convergence happens near cyclones at low pressure centers and promotes upward motion and instability, while divergence happens near anticyclones at high pressure centers and promotes downward motion of air and stability. Rigid boundaries for these two processes are the surface and tropopause.

Convergence happens near (terms) at low pressure centers and promotes (term) motion and (term), while divergence happens near (terms) at high pressure centers and promotes (term) motion of air and (term). Rigid boundaries for these two processes are the TERM and TERM.

Clear skies

Are high pressure centers associated with clouds or clear skies?

Clouds

Are low pressure centers associated with clouds or clear skies?