gy 101

1. What do the following cloud prefixes mean: a. Stratus: horizontal, may be layered, stable b. Cumulus: vertically developed, unstable c. Cirro: high clouds (above 6km) d. Alto: middle clouds (2

6 km) e. Nimbo: rain producing

11. Explain why a cold, dry air mass produces a higher surface pressure than a warm, humid air mass.

A cold, dry air mass will be denser than a warm, humid air mass, and cold air tends to be higher pressure than humid air, so a cold, dry air mass will exert more surface pressure in the atmosphere.

13. What is Precipitation fog?

Cool, rainy days -Rain evaporates, which cools the air and raises the dew point. -Air becomes saturated and fog forms.

7. Name and describe the six types of fog.

Cooling air to its dew point: 1. Radiation 2. Valley 3. Upslope 4. Advection -Adding moisture to the air: 5. Evaporation 6. Precipitation

18. T/F. Air moves from low pressure to high pressure.

False -High à Low

11. What is Advection fog?

Formed by the slow horizontal passage of relatively warm, moist, stable air over a colder (sometimes wet) surface. -EX: California: horizontal movement of warm air over the colder water surface.

28. A gradual pressure gradient is associated with what type of pressure system?

Gradual Pressure Gradient = Weaker Winds = High Pressure

24. What type of pressure is associated with divergence at the surface?

High Pressure

30. An anticyclone is associated with what type of pressure system?

High Pressure

31. A cyclone is associated with what type of pressure system?

Low Pressure

2. Cirrostratus clouds cause a unique feature around the sun and moon, what is this feature?

Produce halos around the sun and moon.

14. What type of fog is produced for the cooling of land after sunset?

Radiation Fog

26. Understand the temperature profiles for the following types of precipitation:

Rain: snow falls into warm air and melts into rain -Snow: precipitation falls into cold air and it never melts on the way down -Sleet: snow melts as it falls from cloud, refreezes into sleet as it travels through cold air -Freezing Rain: snow melts but retains "super-cooled" property and it freezes when it hits the ground

33. In the northern hemisphere, Coriolis force causes deflection to the ________.

Right

3. What type of weather is associated with high pressure and low pressure?

High Pressure: no clouds, sunny, no precipitation -Low Pressure: cloudy, rainy, gross

16. At what point in a day is relative humidity the highest? Lowest?

Highest: in the cool morning. -Lowest: in the middle of the afternoon.

23. The shape of a snowflake is dependent of _____________ and ___________.

The temperature and humidity of the air where the snowflake forms.

1. How are winds formed?

When air moves from high pressure to low pressure.

9. What is the standard sea

level pressure in millibars? In inches of mercury? In pounds per square inch? -1013.25 mb (hPa) -29.92 in

19. The dry adiabatic lapse rate is constant, at __ degrees C / 1000m.

10 degrees C / 1000m

38. What rate is used to adjust differing elevations?

10 mb = 100 m Circulation of the Atmosphere

9. What is the Relative Humidity when the air is saturated?

100%

27. What does it mean if the air is absolutely stable? What is the temperature profile associated with this?

Absolutely Stable: the parcel of air is COOLER than the environment at all altitudes. -ELR < DALR -Clouds in this environment will be widespread with little vertical development. -There will be little precipitation, if any at all.

28. What does it mean if the air is at absolute instability? What is the temperature profile associated with this?

Absolutely Unstable: the parcel of air is WARMER than the environment at all altitudes. -ELR > DALR -Clouds in this environment will be Cumulus; clouds will keep building as long as moisture is supplied.

25. What is the name given to the process whereby the temperature changes without the addition or subtraction of heat?

Adiabatic Temperature Change

15. What type of fog is associated with horizontal movement of warm moist air across a colder surface?

Advection Fog

8. What is Radiation fog?

Also known as ground fog. -Formed by the cooling of land after sunset by thermal (infrared) radiation in calm conditions.

22. What is virga?

Any form of precipitation that does not reach the ground. -It evaporates as it falls through the atmosphere. -Occurs mostly in the summer.

20. If a raindrop becomes too large, what will occur?

As a large drop falls through the atmosphere, it will collide with smaller drops, thus adding to the size of the original drop. If the rain drop gets large enough it will fall to the ground. -If it gets too large, it will break into smaller droplets. -A drop must be larger than the other drops to be an efficient collider. -If the drop is too big, it will be less efficient because it creates high pressure that pushes smaller drops out of the way.

21. Does Collusion Coalescence occur in cold clouds or cool clouds?

Cool clouds because the rain drops have to be able to collide inside the cloud.

10. Explain why air pressure decreases with an increase in altitude in the Troposphere.

At higher elevations, there are fewer air molecules above a given surface than a similar surface at lower levels.

5. Why is the mixing ratio calculation not affected by changes to pressure and temperature?

Because it is measure in units of mass it is not affected by changes in temp and pressure.

34. Absolute instability produces what type of clouds?

Clouds in this environment will be Cumulus; clouds will keep building as long as moisture is supplied. Clouds and Precipitation

32. What type of clouds and precipitation is associated with a stable atmosphere?

Clouds in this environment will be widespread with little vertical development. -There will be little precipitation, if any at all.

9. What is Valley fog?

Cold air forms at high elevation and it drains into a valley below. -The cold air drainage reduces air temperature in valley to condensation point.

20. What is the level at which clouds form called? Why do clouds form here?

Condensation Lifting Level (CLL) -The air has cooled to its dew point causing saturation.

29. What does it mean if the air is Conditionally unstable? What is the temperature profile associated with this?

Conditional Instability: the parcel of air is cooler than the environment up until the condensation lifting level, but with the addition of latent heat above the condensation lifting level it becomes warmer. -DALR < ELR < WALR -Conditionally unstable air will not rise on its own, it needs a lifting mechanism.

12. Compare convergence and divergence.

Convergence: winds blowing into a region, air piles up, must begin to flow upward, the pressure at the surface will increase when there is a net convergence in a region. -Divergence: winds blowing out of a region, associated with a decrease in pressure.

21. If air is diverging at the surface, what is it doing aloft?

Converging

22. If air is diverging aloft, what is it doing at the surface?

Converging

14. Briefly describe how the Coriolis force modifies the movement of air.

Coriolis Force is the deflection of winds caused by the rotation of the Earth. -Because the Earth is moving on its axis, the wind is deflected to the right in the Northern hemisphere, to the left in the Southern hemisphere, zero at the equator and maximum at the poles.

10. What is Upslope fog?

Created when relatively humid air moves up a gradual slope. -Because of the upward movement, air expands and cools. -If the dew point is reached, an extensive layer of fog forms.

3. What type of cloud is associated with thunderstorms?

Cumulonimbus

5. The only type of cloud that can breach the tropopause is?

Cumulonimbus

4. What type of cloud is associated with an anvil top that is composed of cirrus clouds?

Cumulonimbus: heavy rainfall, thunder, lightning, hail, and tornadoes

2. What are the units of absolute humidity?

D = Mass of H2O Vapor (grams) / Volume of air (m3 ) -grams/m3

19. If air is converging at the surface, what is it doing aloft?

Diverging

20. If air is converging aloft, what is it doing at the surface?

Diverging

28. Clouds are typically seeded with what type of substance?

Dry Ice or Silver Iodide Air Pressure

18. What is the average environmental lapse rate?

ELR: change in measured air temperature with height -Tropospheric Average: 6.5 degrees C / 1000m

32. What causes the Coriolis force?

Earth's rotation on its axis

26. What is the pressure gradient force?

Earth's system wants to return to equilibrium, so the air will move from high to low pressure. -Gradient: difference in pressure over a distance -Steep Pressure Gradient = Low Pressure -Gradual Pressure Gradient = High Pressure

17. What are the three types of lapse rates associated with adiabatic temperature change?

Environmental Lapse Rate: The air around the bubble -Dry Adiabatic Lapse Rateà The bubble -Wet Adiabatic Lapse Rateà The bubble

8. What dominates first in Saturated Vapor Pressure?

Evaporation

16. What type of fog is common in early fall, and can commonly be seen in or around pools and lakes?

Evaporation (Steam) Fog

25. What is the name of the convergence zone that migrates through the tropical latitudes?

Intertropical Convergence Zone (ITCZ)

15. The increase in temperature with height is called ________.

Inverse Lapse Rate

27. What are four ways that humans have attempted to alter precipitation patterns? 1. Cloud Seeding

Involves injecting a material into non-precipitating clouds (dry ice and silver iodide) 2. Fog Dispersal -Aid visibility around airports -Heating air; mixing air 3. Hail Suppression -Hail Cannon with dynamite at base of funnel 4. Frost Prevention -More economic losses occur due to freeze damage in the U.S. than to any other weather related hazard -Heaters; fans to mix air if it is a little warmer 10 meters above the ground

29. What is the name for lines that connect areas of equal pressure?

Isobars

13. Write a generalization relating to the spacing of isobars to the speed of winds.

Isobars: lines that indicate areas of equal pressure on a map -The closer the isobars are to each other, the steeper the pressure gradient, the stronger the winds (typically low pressure). -The farther apart the isobars, the weaker the pressure gradient, the weaker the winds (typically high pressure). -Winds move perpendicular to isobars.

15. What effect does the Coriolis Force have on the movement of wind in relation to isobars?

It causes air to travel parallel to isobars.

3. Why is absolute humidity not used in forecasting?

It is dependent on volume of the air parcel which changes depending on the location.

25. How is hail formed?

It is formed when updrafts carry a particle into the colder reaches of a cloud and the liquid water coats the particle. This is repeated multiple times: snowflake goes down and melts a bit, updrafts push it up and freeze it, goes down and melts, etc. and it forms a mixture of ice and water.

6. Why is the mixing ratio rarely used in forecasting?

It is very hard to calculate the mass by direct sampling.

34. In the southern hemisphere, Coriolis force causes deflection to the ________.

Left

8. Warm Air = ________ Pressure

Low

23. What type of pressure is associated with convergence at the surface?

Low Pressure

2. What is the difference between low pressure and high pressure?

Low Pressure: When air rises, it leaves behind an air of lower pressure because the upward-moving air is not pressing down so hard on the surface. -High Pressure: Areas of high pressure are formed when air is sinking back down, and so pushing down harder on the surface.

4. What are the units for the mixing ratio calculation?

Mixing Ratio = Mass of H2O Vapor (grams) / Mass of Dry Air (kg)

10. _______ and ________ cause the relative humidity to change.

Moisture Content -Temperature

14. The decrease in temperature with height is called ________.

Normal Lapse Rate

24. What is graupel?

Occurs when an ice crystal takes on additional mass by accretion of super-cooled cloud droplets. -Contains air pockets and has a spongy texture.

24. Describe each of the four uplift mechanisms.

Orographic Lifting: Air is forced to rise over a mountainous barrier -Frontal Wedging: Warm air is less dense and rides up over cold air. Cold air is more dense and wedges underneath warm air. -Convergence: A pile-up of horizontal air flow results in upward movement. -Localized Convective Lifting: Unequal surface heating causes localized pockets of air to rise because of their buoyancy.

37. The geostrophic winds are caused by the equilibrium of _________ and _________.

Pressure Gradient Force and Coriolis Force

6. Does pressure increase or decrease with altitude?

Pressure decreases with altitude increase. 7. Cold Air = _______ Pressure -High

27. A steep pressure gradient is associated with what type of pressure system?

Steep Pressure Gradient = Strong Winds = Low Pressure

5. What are the main two factors that affect atmospheric pressure?

Temperature and Water Vapor content

36. Coriolis force is zero at _________, thus tropical cyclones cannot form in this region.

The Equator

35. Where is the Coriolis force at its maximum?

The Poles

13. What occurs when the air temperature and dew point temperature are equal?

The air is fully saturated.

16. Explain the formation of a geostrophic wind.

The combination of the Pressure Gradient Force and the Coriolis Force -As wind gains speed, the deflection increases until the Coriolis force equals the pressure gradient force. At this point, the wind will be blowing parallel to the isobars. When this happens, the wind is referred to as Geostrophic.

19. How do updrafts help in the formation of precipitation?

The updraft process carries smaller cloud droplets up into the cloud while larger droplets stay suspended within the cloud.

17. What is the role of condensation nuclei in formation of precipitation?

These are usually tiny particles in the air that provide a surface for water vapor to condense onto. -Without condensation nuclei, the surface tension of a water droplet is too much for the droplet to stay together. The nuclei enable condensed droplets to grow large enough to become cloud or rain droplets.

12. T/F. The dew point temperature will never be greater than the air temperature.

True

21. T/F. The condensation lifting level varies from region to region.

True

30. T/F. The atmosphere is stable when the environmental lapse rate is less than the wet adiabatic lapse rate.

True

7. What is the difference between vapor pressure and saturated vapor pressure?

Vapor Pressure is the pressure exerted by a vapor with its condensed phases at a given temperature in a closed system. But Saturated Vapor Pressure is the equilibrium between the number of molecules evaporating and the number of molecules condensing.

11. Which air parcel will hold more water vapor, cold or warm?

Warm air "holds" more water vapor.

12. What is Evaporation fog?

Warm water and cool air -Water evaporates but then condenses in the cool atmosphere -Common in: early fog

33. Absolute instability occurs when a parcel of air is warmer or colder than the environment at all levels.

Warmer(?)

1. What causes water to change state? Keep in mind the kinetic energy and the molecular structure.

Water changes state due to gaining or losing heat from its environment. This change in heat (kinetic energy) causes the molecules of water to either break apart or come closer together changing the state of the molecules.

26. Why is moist air less dense than dry air?

Water vapor is a relatively light gas when compared to diatomic Oxygen and diatomic Nitrogen. Thus, when water vapor increases, the amount of Oxygen and Nitrogen decrease per unit volume and thus density decreases because mass is decreasing.

22. Why is the wet adiabatic lapse rate highly variable?

When the water vapor condenses at the lifting condensation level, latent heat of condensation is liberated, reducing the rate of adiabatic cooling. -Because the amount of latent heat released depends on the quantity of moisture in the air, the wet adiabatic lapse rate (WALR or MALR) varies.