1. Weather Review

2. Question 1 What is dew point?
The dew point is the temperature to which air must be cooled at constant pressure to reach saturation.
Condensation cannot occur until air is saturated.
Condensation occurs when matter changes state from a gas to a liquid.
measurement of how rapidly or slowly molecules move around
the temperature to which air must be cooled at constant pressure to reach saturation
the amount of water vapor in air
the transfer of energy that occurs because of a difference in temperature between substances

3. Question 2
A dark flat layered cloud that continuously produces rain would be considered a…?
Stratus = flat
Nimbo = rain
Cumulus cloud
Stratus cloud
Cirrus cloud
Nimbostratus cloud
Cumulonimbus cloud

4. Question 3 What does a barometer measure?
An instrument that measures wind speed and direction
An instrument that measures temperature
An instrument that measures air pressure
An instrument that measures relative humidity
Check out quizlet 12.2 if you need some help.

5. Question 4 What does a Hygrometer/ psychrometer measure?
Check out quizlet 12.2 if you need some help.

6. Question 5 What does an anemometer measure?
Check out quizlet 12.2 if you need some help.

7. Question 6 What does an Thermometer measure?
Check out quizlet 12.2 if you need some help

8. Question 7
Which air mass would cause a hot, humid spell in the northeastern United States during the summer?
The main types of air masses are:
warm and dry
continental tropical (cT)
warm and humid
maritime tropical (mT)
cold and dry
continental polar (cP)
cold and humid
maritime polar (mP)
Very cold and dry
arctic (A)
maritime tropical
maritime polar
continental tropical
continental polar

9. Question 8 What is an isobar? A line of equal elevation
A line of equal temperature
A line of equal air pressure
A line of equal humidity
Very similar to contour lines which are representations of equal elevation isobars are lines representing areas of equal air pressure.

10. Question 9 What does it mean if isobars are close together?
Isobars that are close together indicate a large pressure difference over a small area and thus, strong winds as the air pressure tries to balance itself out and rush from one area to the other.
Isobars that are spread far apart indicate a small difference in pressure which equates to light winds.
Winds will be strong
Winds will be weak
Temperature will rise
Temperature will fall
Precipitation will occur

11. Question 10
Continental tropical (cT) air masses can be characterized by
cold and dry air
hot and dry air
cold and damp air
warm and moist air

12. Question 11 What is a front?
A front is the narrow region separating two air masses that can create big weather changes.
The air masses have different densities caused by differences in temperature, pressure, and humidity.
4 main types of fronts:
cold fronts, warm fronts, stationary fronts, and occluded fronts.
a region where temperatures and humidities stay the same
an area where warmer air slides under colder air
a boundary between two air masses
a vertical zone between colder and warmer air

13. Question 12 What is a stationary front?
Stationary Fronts two air masses meet and neither advances (moves) into the other’s territory.
They seldom have extensive clouds or heavy precipitation patterns.
In NC they are usually a mix of sun & clouds with possible afternoon t-storms
a front that moves continuously
a front that takes over an occluded front
a front that takes over a cold front
a front that does not move

14. Other Fronts Cold front = thunderstorms then clear
Cumulonimbus then cumulus
Warm front = sustain rain
Stratus type clouds
Stationary front = two air masses meet either advances
Occluded front = Warm air sandwiched between two cold air masses. Cold front overtakes a warm air mass.

15. Question 13
Why do thunderstorms often occur in the afternoon during the summer?
Surface cooling throughout the day causes unstable conditions in the troposphere.
Surface warming throughout the day causes unstable conditions in the troposphere.
Surface cooling throughout the day causes stable conditions in the troposphere.
Surface warming throughout the day causes stable conditions in the troposphere.

16. Question 13
Summer = warm humid conditions. The air at the surface heats quickly and gathers lots of moisture and begins to rise from the surface throughout the day.
Then at higher altitudes it quickly cool vertically to produce the type of clouds associated with thunderstorms.
This vertical lifting of air is considered “unstable”.

17. Question 14 What data do infrared satellites use to create images?
temperature measurements
pressure measurements
humidity measurements
visible light measurements
Infrared Imagery
Infrared imagery detects differences in thermal energy, which are used to map either cloud cover or surface temperatures.

18. Question 14 The colder the cloud top the higher it is.
Strength of a thunderstorm is related to its height. The higher a cloud (this is vertical cloud so the bottom is near the Earth’s surface) the more potential for hazardous storms.
infrared imagery can be used to estimate a storm’s potential for severe weather.

19. Question 15
If there was 5 grams of water in air (specific humidity) that can hold 50 grams of water what would the relative humidity be?
Relative humidity is the amount of water vapor in a volume of air compared to how much water vapor that volume of air can hold.
Relative humidity is expressed as a %.
How much water the air is holding / how much water the air could hold at that temperature times 100. 5%
10%
20%
50%

20. Question 16
If both wet-bulb and dry-bulb thermometers on a psychrometer read the same, the air is
dry
sublimating
saturated
evaporating
A psychrometer is a device which is used to measure the relative humidity at a given location or place. It is also referred to as the wet and dry bulb thermometer.
For "dry" air, air that is less than saturated (i.e., air with less than 100 percent relative humidity), the wet-bulb temperature is lower than the dry-bulb temperature due to evaporative cooling.

21. Question 16
The greater the difference between the wet and dry bulb temperatures, the drier the air and lower the relative humidity.
If both thermometers read the same value then the air must be saturated and thus has reached the dew point temperature or 100% relative humidity where condensate and rain will form.

22. Question 17
What is air mass #6 in this picture? A. Continental Tropical B. Maritime Tropical C. Continental Maritime D. Maritime Polar E. Continental Polar
1 = Maritime Polar 2 = Continental Polar
3 = Maritime Polar 4 = Maritime Tropical
5 = Continental Tropical

23. Question 18
Which of the following are not used by forecasters to locate fronts?
changes in wind direction
changes in wind speed
temperature changes
dew point changes
As fronts pass through an area there are big weather changes.
The air masses have different densities caused by differences in temperature, pressure, and humidity.

24. Question 18 They’ll also have different wind directions.
Notice on the picture on the left the differences in the station models outside the red line and within the redline.

25. Question 19 An air mass takes on its source region’s
temperature and humidity.
clouds and wind.
landforms.
elevation.
An air mass is a large body of air that takes on the characteristics of the area over which it forms.
Air masses that form over land are generally drier than those that form over water.

26. Question 19
Air masses also take temperatures from the regions they form.
Tropical being warmer and polar colder.
The region over which an air mass forms is called the “source region”.

27. Question 20 Maritime air masses originate over…? land. the tropics.
oceans.
the equator
the poles.

28. Question 21 What is the picture to the right illustrating?
A stationary Front
Evaporation
A warm Front
Sublimation
Orographic Lifting
Orographic lifting occurs when wind encounters a mountain and the air has no place to go but up.
The air expands and cools at higher altitude resulting in cloud formation.

29. Question 22
Which of the following statements describes a High pressure system correctly?
Air sinks and at the surface it spreads away from the center.
The Coriolis effect causes the air around a high to move in a clockwise direction in the northern hemisphere.
It produces stable weather because air is sinking thus no clouds can form.
Air sinks, moves clockwise, stable weather
Air rises, moves counter clockwise, unstable weather
Air sinks, moves counter clockwise, stable weather
Air rises, moves clockwise, unstable

30. Question 23
Which of the following statements describes a low pressure system correctly?
Low-Pressure Systems
In a low, air rises and flows toward the center and then upward.
Moves in a counterclockwise direction.
A wave cyclone, one of the main producers of inclement weather in the middle latitudes, usually begins along a stationary front.
Air sinks, moves clockwise, stable weather
Air rises, moves counter clockwise, unstable weather
Air sinks, moves counter clockwise, stable weather
Air rises, moves clockwise, unstable

31. Question 23
As air rises in the center of the low pressure system it draws more air from the surface into the center of the system.
This rising air is considered “unstable” because it has the potential for creating precipitation weather as the air cools and forms clouds at higher altitude.
Often two fronts will form out from the low pressure center that chase each other around the center of the system.

32. Question 24
If you needed to determine how tall clouds were what device would you use? A. Visible Satellite imagery B. Infrared Satellite imagery C. Doppler Radar D. Ceilometer E. Fujita Scale
Infrared imagery detects differences in thermal energy, which are used to map either cloud cover or surface temperatures.
The colder the cloud top the higher it is. The cloud itself insulates the heat coming from the Earth and blocking that heat from reaching the sensors on the satellite thus taller clouds appear cooler.
Strength of a thunderstorm is related to its height.

33. Question 25 What are data points I and IV?
Current weather / cloud cover
Dew point / current weather
Dew point / pressure
Wind barb / temperature
Current weather / dew point
Wind barb
Pressure
Cloud cover
Temperature
Dew point
In between IV and V is current weather conditions