Lesson 8 Weather Theory

Question 1

What is the Earth’s atmosphere?

Answer 1

A cloud of gas and suspended solids extending from the surface, becoming thinner with distance, held by gravitational pull.

Question 2

What is an air parcel?

Answer 2

An imaginary volume of air to which any or all of the basic properties of atmospheric air may be assigned.

Question 3

Name the five concentric layers of the Earth’s atmosphere.

Answer 3

• Troposphere
• Stratosphere
• Mesosphere
• Thermosphere
• Exosphere

Question 4

What is the altitude range of the troposphere?

Answer 4

Extends up to about 36,000 feet high.

Question 5

Where does almost all weather occur in the atmosphere?

Answer 5

In the troposphere.

Question 6

What happens to temperature in the stratosphere as altitude increases?

Answer 6

Temperature increases with height.

Question 7

What is the primary characteristic of the mesosphere?

Answer 7

Temperature decreases with height.

Question 8

What is the thermosphere known for?

Answer 8

It is known as the upper atmosphere, where temperature can reach as high as 2000 degrees Celsius.

Question 9

What is the exosphere?

Answer 9

The outermost layer of the atmosphere where atoms and molecules escape into space.

Question 10

What is the standard sea level pressure according to the International Standard Atmosphere?

Answer 10

29.92” HG or 1013.2 mb.

Question 11

Define temperature in terms of molecular motion.

Answer 11

A value representing the kinetic energy of the atoms and molecules within matter.

Question 12

What is the average lapse rate in the atmosphere?

Answer 12

2 Degrees Celsius/1,000 feet.

Question 13

Fill in the blank: The dry adiabatic lapse rate is ______.

Answer 13

3C/1,000ft.

Question 14

What is a temperature inversion?

Answer 14

A condition where temperature increases with altitude instead of decreasing.

Question 15

How was atmospheric pressure historically measured?

Answer 15

In inches of mercury by a mercurial barometer.

Question 16

What instrument is commonly used today to measure atmospheric pressure?

Answer 16

Aneroid barometer.

Question 17

What happens to pressure as altitude increases?

Answer 17

Pressure decreases.

Question 18

What is a pressure system?

Answer 18

An area of higher or lower pressure compared to surrounding areas.

Question 19

What does a high pressure system usually indicate?

Answer 19

Good weather.

Question 20

What does a low pressure system usually indicate?

Answer 20

Bad weather.

Question 21

Define Pressure Gradient Force (PGF).

Answer 21

The force that drives wind due to pressure differences.

Question 22

What is the effect of the Coriolis force on wind in the northern hemisphere?

Answer 22

It deflects air to the right of its path.

Question 23

True or False: Friction between wind and terrain increases wind speed.

Answer 23

False.

Question 24

What causes local wind patterns?

Answer 24

Heating and cooling of the ground.

Question 25

What is a sea breeze?

Answer 25

A coastal local wind that blows from sea to land.

Question 26

What is a land breeze?

Answer 26

A coastal breeze blowing from land to sea.

Question 27

What is relative humidity?

Answer 27

The ratio of water vapor actually in the air compared to the amount it could hold.

Question 28

What does dew point indicate?

Answer 28

The temperature at which water vapor in the air condenses into water.

Question 29

What are the physical states of water in the atmosphere?

Answer 29

* Liquid * Solid * Gaseous

Question 30

What is precipitation?

Answer 30

Any form of water particles that falls from the atmosphere and reaches the ground.

Question 31

What are the requirements for precipitation to occur?

Answer 31

* Water Vapor * Sufficient lift * Growth process for cloud droplets

Question 32

What is drizzle?

Answer 32

Very small water droplets, smaller than 0.02 inches in diameter.

Question 33

Fill in the blank: Rain that evaporates before hitting the ground is known as ______.

Answer 33

virga.

Question 34

What can cause freezing rain?

Answer 34

When the temperature of the surface is below freezing.

Question 35

What are ice pellets?

Answer 35

Rain that freezes as it passes through colder air.

Question 36

What is virga?

Answer 36

Precipitation that evaporates before reaching the ground.

Question 37

What occurs when rain falls through a temperature inversion?

Answer 37

It may freeze as it passes through the underlying cold air and falls as ice pellets.

Question 38

How do ice pellets or hail form?

Answer 38

Freezing water droplets are carried up and down by drafts inside cumulonimbus clouds.

Question 39

What is snow?

Answer 39

Precipitation in the form of ice crystals that falls at a steady rate or in snow showers.

Question 40

What conditions lead to the formation of dew?

Answer 40

Cool, clear, calm nights where the temperature drops below the dewpoint.

Question 41

What is frost?

Answer 41

Moisture that freezes upon condensation due to cold air.

Question 42

What are clouds?

Answer 42

Visible indicators of moisture in the atmosphere, formed when water vapor condenses.

Question 43

What is required for cloud formation?

Answer 43

Adequate water vapor, condensation, and a method for cooling the air.

Question 44

What are condensation nuclei?

Answer 44

Miniscule particles like dust, salt, and smoke that aid in moisture condensation.

Question 45

How are clouds classified?

Answer 45

By height, shape, and characteristics.

Question 46

What is fog?

Answer 46

A cloud that is at the surface of the Earth.

Question 47

What causes fog to form?

Answer 47

Cooling of air near the ground to the air's dew point.

Question 48

Name a type of fog classified by its formation.

Answer 48

Radiation Fog, Advection Fog, Ice Fog, Steam Fog, Upslope Fog, Precipitation Fog, Ground Fog.

Question 49

What is radiation fog?

Answer 49

Fog that forms on calm, cool nights as the ground cools the surrounding air.

Question 50

What is advection fog?

Answer 50

Fog formed when warm moist air moves over a cooler surface.

Question 51

What is ice fog?

Answer 51

Fog that occurs at extremely cold temperatures, typically below -31°C.

Question 52

What is steam fog?

Answer 52

Fog that forms when cold dry air moves over warm water.

Question 53

What is upslope fog?

Answer 53

Fog that forms when stable air is forced up a slope by wind.

Question 54

What is precipitation fog?

Answer 54

Fog formed when precipitation cools the air to saturation.

Question 55

What is atmospheric stability?

Answer 55

The atmosphere's resistance to vertical movement.

Question 56

What characterizes a stable atmosphere?

Answer 56

It moves, but vertical movement is more difficult.

Question 57

What happens in an unstable atmosphere?

Answer 57

Small vertical air movements tend to become larger, resulting in turbulence and severe weather.

Question 58

What is adiabatic heating?

Answer 58

The process where rising air expands and cools due to decreased pressure with altitude.

Question 59

What is the average rate of temperature change with altitude?

Answer 59

2ºC per 1,000 feet.

Question 60

What is the dry lapse rate?

Answer 60

3ºC per 1,000 feet.

Question 61

What is the moist lapse rate?

Answer 61

1.1ºC to 2.8ºC per 1,000 feet.

Question 62

What is the greatest instability in the atmosphere?

Answer 62

Occurs when the air is moist and warm.

Question 63

What is the standard adiabatic lapse rate?

Answer 63

2ºC per 1,000 feet.

Question 64

What are the four types of pressure systems?

Answer 64

Not specified in the text.

Question 65

What are the three biggest factors that affect wind?

Answer 65

Not specified in the text.

Question 66

What is relative humidity?

Answer 66

Not specified in the text.

Question 67

How does a cloud form?

Answer 67

Through condensation of water vapor in rising currents of air.

Question 68

What is the difference between stable and unstable air?

Answer 68

Stable air resists vertical movement, while unstable air encourages it.