Atmospheric Forces & The Geostrophic Wind | Prelab 14

vector

an arrow used to graphically represent the magnitude (strength) and direction of a force.

A longer vector length equals a greater magnitude

(A longer vector length equals a greater TERM).

pressure gradient force

A force directed from high to low pressure with the direction perpendicular to isobars or isohypses on a pressure surface.

friction

A force that occurs when two objects in contact move past one another. It acts in the direction opposite of motion, and it always slows the wind.

coriolis force

an apparent force that occurs because of the earth’s rotation

friction layer

the layer where friction is important. Above around 1-3km, it is minimal and ignored.

centrifugal force

an apparent force caused by circular or curved motion. directed outwards, away from the center of rotation

acceleration

when forces are not in balance, the wind undergoes (term) and changes speed and/or direction. If the wind is at a constant speed and direction, (same term, do not retype) is not occuring.

Coriolis force expression: CF=2(omega)Vsin(phi)
phi→ latitude

omega→ how fast the earth spins 7.292×10^-5 rad/s

V→ wind speed

((Coriolis force expression: CF=2(omega)Vsin(phi)
Phi → term

omega→ how term the earth terms (####x##^# unit/unit)

V → term term ))

pressure gradient force

PGF is an abbreviation for…

friction

Fr is an abbreviation for…

Coriolis force

CF is the abbreviation for…

centrifugal force

Ce is the abbreviation for.. .

The pressure gradient force is the key force for atmospheric motion. It is directed from high to low pressure, and it runs perpendicular to isobars/contours, accelerating air towards low pressure. The magnitude/strength of the force is inversely proportional to isobar/contour spacing.

((The pressure gradient force is the key force for atmospheric motion. It is directed from (term) to (term) pressure, and it runs (term) to isobars/contours, (terming) air towards low pressure. The magnitude/strength of the force is (term term) to isobar or contour spacing.

geostrophic wind

a theoretical wind that would occur if the Coriolis force and pressure gradient force were exactly in balance in the upper atmosphere

Evolution of the geostrophic wind:
1. Coriolis force is zero, but a strong PGF is present, though the parcel remains static.
2. The PGF accelerates the parcel from high to low pressure. When the parcel starts to move, the Coriolis force starts to pull it to the right.

3. As the speed increases, the Coriolis force increases at a 90 degree angle to the movement and pulls the movement further to the right.

4. Eventually the Coriolis force becomes equal and opposite to the PGF. The forces are balanced and the air parcel is now in equilibrium. The net force on the parcel is zero and there is no further acceleration. The parcel moves at a constant speed and direction. This balanced force is the geostrophic wind

(Evolution of the geostrophic wind:
1. CF is (Term), but a strong PGF is present, though the parcel remains static.

2. The PGF (terms) the parcel from high to low pressure. When the parcel starts to move, the Coriolis force starts to pull it to the (term).

3. As the speed increases, the Coriolis force (terms) at a (## unit term) to the movement and pulls the movement further to the (term).

4. Eventually, the Coriolis force becomes (term) and (term) to the PGF. The forces are (termed) and the air parcel is now in (term). The net force on the parcel is (term) and there is (term further acceleration). The parcel moves at a (term) speed and direction. This balanced force is the (term term). ))

In the Northern Hemisphere, the geostrophic wind is parallel to the pressure/height contours with the high pressure on the right and the low pressure on the left. It is the final state of the wind without other forces acting on it.

(In the Northern Hemisphere, the geostrophic wind is TERM to the pressure/height contours with the high pressure on the TERM and the low pressure on the TERM. It is the final state of the wind TERM other forces acting on it)

Rules for drawing force vectors:

PGF is always perpendicular to isobars/contours and always points from high to low pressure

CF is always 90 degrees to the right of the wind vector in the Northern Hemisphere

Frictional force always points in the opposite direction of the wind and acts to decrease the speed of the wind

Centrifugal force/Ce is proportional to how fast and tight the turn is and directed outward from the center of rotation.

The geostrophic wind always follows the isobars or height contours with low pressure/low height on the left in the Northern Hemisphere

(Rules for drawing force vectors:
PGF is always (term) to isobars/contours and always points from (term) to (term) pressure

CF is always (## unit) to the (term) of the wind vector in the Northern Hemisphere
Frictional force always points in the (term) direction of the wind and acts to (term) the speed of the wind

Centrifugal force/Ce is proportional to how (term) and (term) the turn is and directed (term) from the center of rotation

The geostrophic wind always follows the isobars or height contours with (term pressure/term height) on the (term) in the Northern Hemisphere