Weather (atmosphere)

Question 1

Air flow aorund high/low pressure systems

Answer 1

Low - inward, upward, counterclockwise

High - Outward, downward, clockwise

Question 2

Low/high pressure system characteristics

Answer 2

Low Pressure

Rising air
Cloudiness
Precipitation
bad weather

High Pressure

Descending air
dissipation of cloudiness
good weather

Question 3

Fronts & descriptions

Answer 3

Cold: mass of cold dense stable air advances and replaces a body of warmer air

Occluded: fast moving cold front catches up with slow warm front (cold or warm front occlusion)

Warm: boundary area formed when warm air mass contacts and flows OVER a colder air mass

Stationery: forces of two air masses are about equal. Boundary or front that separates them remains stationary and influences local wx for days; a mixture of typical wx from warm and cold fronts

Question 4

General warm and cold front characteristics

Answer 4

Cold: as the front passes expect towering cumulus or cumulonimbus, heavy rain with lightning, thunder, or hail, tornados possible. Durring passage poor visibility, winds variable/gusting, temp/dew point spreadand pressure drop

Warm: as the front passes expect straiform clouds, drizzle, low ceilings, poor visibility, variable winds, rise in temp

All depends on the amount of mositure , stability of air that is forced upward, slope of the front, speed of the movement, and upper wind flow

Question 5

What is a trough? Ridge?

Answer 5

Trough: Elongated area of low pressure

Ridge: Elongated area of high pressure

Question 6

Standar temps and pressures

Answer 6

59F/15C - 29.92 inches of Hg/1013.2 millibars

Question 7

Isobars on surface weather chart/constant pressure chart

Answer 7

Spacing shows how steep or shallow pressure gradient is

Close: steep gradient; higher wind speeds

Farther: shallow/lower speeds

Question 8

What force deflects winds to the right in northern hemisphere and to the left in the southern?

Answer 8

Coriolis

Question 9

Pressure lapse rate per altitude

Answer 9

1 inch Hg / 1,000 feet

Question 10

Dew Point means?

Answer 10

temperature to which air must be cooled to attain the state of saturation

Question 11

What factor primarily determinds the type and vertical extent of clouds? WHy is it important?

Answer 11

Stability!

Stability depends on atmosphere’s ability to resist vertical motion

Unstable: turbulent airflow, convective activity, vertical clouds, severe weather

Question 12

Effects of stable and undstable air on clouds, turbulence, precip, vis

Answer 12

Stable / unstable
Clouds - stratiform / cumuliform
Turbulence - smooth / rough
Precip - Steady / showery
Vis - Fair to poor / good

Question 13

During preflight planning, what info should you be aware of for icing?

Answer 13

Location of fronts
Cloud layers
Freezing levels
Air temp and pressure

Question 14

What is the freezing level?

Answer 14

Lowest altitude in the atmosphere over a location where temp is 0c/32f

Question 15

What conditions necessary for structural icing?

Answer 15

Visible moisture / below freezing temps

Question 16

Two categories of icing

Answer 16

Structural or induction

structural: on aircraft surfaces
Induction: in the engine’s induction system

Question 17

Structrual icing types

Answer 17

Clear, rime, mixed ice

Question 18

You encounter icing, now what?

Answer 18

Leave the area of visible moisture: climb or descend above or below cloud bases

turn away / different heading

Question 19

Frost: is it bad?

Answer 19

Yes. It makes the surfaces rough and spoils smooth airflow arond them causing slower airflow and reduces lift

Question 20

Thunderstorm formation factors

Answer 20

a. sufficient water vapor
b. unstable lapse rate
c. rising air

Question 21

Thunderstorm stages

Answer 21

1. cumulus: updrafts cause raindrops to get bigger
2. Mature - rain, lightning, maybe roll clouds
3. Dissipating - downdrafts and rain begin to dissipate

Question 22

Temperature inversion

Answer 22

Increase in temp with height / reversal of normal decrease with height

Question 23

How does fog form?

Answer 23

Temp and dewpoint become identical or nearly so

Cooling of air (radiation fog, advection fog, upslope fog)

Adding moisture and elevating the dewpoint (frontal fog or steam fog)

Question 24

Name types of fog

Answer 24

Radiation, advection, upslope, frontal, precipitation induced, steam

Question 25

What causes radiation fog?

Answer 25

The ground cools the adjacent air to the dewpoint on calm clear nights

Question 26

What causes advection fog?

Answer 26

Results from the transport of warm humid air over a cold surface - primairly along coastal areas during the winter

Question 27

What causes upslope fog?

Answer 27

Result of mosit stable air being cooled adiabatically as it moves up sloping terrain. Wind stops, fog goes away. Can be very dense and extends to high altitudes

Question 28

What is wind shear, where is it likely to occur

Answer 28

Change of velocity and/or direction either horizontal or vertical.

a. low level temp inversion
b. frontal zone or t-storm
c. clear air turbulence (CAT) at high levels associated with a jet stream or strong circulation