Meteo 122 Exam 2 Concept Check

How does hail form? What factors govern the ultimate size of hailstones

In cumulonimbus clouds, they begin as small ice pellets and move through the addition of supercooled water. Size is determined by it hitting a down draft or the up draft not being able to support it

What are the two criteria by which clouds are classified?

Form and height

Unlike winds aloft, which blow nearly parallel to the isobars, surface winds generally cross the isobars. Explain what causes this difference.

Friction causes the difference as it can not alter the direction of the winds aloft.

Explain how lenticular clouds form

Image result for how to lenticular clouds form Where stable moist air flows over a mountain or a range of mountains, a series of large-scale standing waves may form on the downwind side. If the temperature at the crest of the wave drops to the dew point, moisture in the air may condense to form lenticular clouds.

Why is the polar jet sometimes referred to as the midlatitude jet stream?

The location of this jet stream occurs in the midlatitudes

What areas of North America experience a pronounced monsoon circulation?

The southwest US and Northwest Mexico

What actually happens when a radiation fog "lifts"?

The sun warms the ground, the lowest layer of air is heated first, and the fog evaporates bottom up

What is Dew-point temperature?

The temperature at which dew will form.

Why is the flow aloft in the midlatitudes predominantly westerly?

The temperature differences between the poles and equator drives these winds. The differences in pressure changes for the polar high and Equatorial low create a pressure gradient force acting against the Coriolis force, creating geostrophic winds

What weather condition would lead you to believe that the air is unstable?

Weather conditions would be towering clouds and accompanied with heavy precipitation

What is the name of the prevailing winds that affect the contiguous United States?

Westerlies

What general weather conditions can we expect when surface pressure is rising? When the pressure tendency is falling?

What general weather conditions are to be expected when the pressure tendency is rising? When the pressure tendency is falling? Rising - This indicates a high pressure center is approaching. Highs are associated with descending, adiabatically warming air - this precludes cloud formation. Thus one should expect clear, fair weather. Falling- A low pressure center is approaching. Since lows are associated with rising air, adiabatic cooling and cloud formation, precipitation is possible. Thus one could expect cloudy, and possibly rainy weather.

Why does adiabatic rate of cooling change when condensation begins?

When condensation occurs, latent heat is released by the vapor/water droplets into the surrounding air

Briefly describe how the Coriolis force modifies air movement.

causes all free moving objects including wind to move to be deflected to the right of their path

List two reasons that explain why polar regions experience meager precipitation.

dominated by high pressure and cold air that holds little moisture

What is supercooled water?

is the process of lowering the temperature of a liquid or a gas below its freezing point without it becoming a solid.

Water's solid phase ice is less dense than liquid water. Why is this property of water important?

water freezes top down, causes effects for daily weather and aquatic life, when ice forms on a water body it slows the rate of freezing at depth if it was the way around aquatic life would be killed in a frozen lake and would alter the Earth's heat budget.

What is average (standard) sea-level pressure, measured in pounds per square inch, millibars, and inches of mercury?

14.70 pounds per square inch; 1,013.25 millibars; 29.92 inches of mercury

What name is given to the process whereby the temperature of air changes without the addition or subtraction of energy?

Adiabatic Temperature

Name two factors that cause air to subside between 20 and 35 degrees latitude

Air cools becomes more dense and sinks and Coriolis force getting stronger with increasing distance from the equator.

After reviewing table 4.1, summarize the relationship between vapor pressure and saturation.

As it gets warmer, the air has more potential to hold more moisture thus increasing saturation. Thats why it's dry in the winter.

Explain why air pressure decreases with an increase in altitude

As we ascend through the atmosphere we find that the air becomes less dense because of the continental decrease in amount of air above.

Distinguish between clouds and fog

Clouds condense and form higher in the air whereas fog is essentially a cloud that has condensed and formed near the ground.

Describe the process of cloud formation

Clouds form when moist, warm rising air cools and expands in the atmosphere. The water vapor in the air condenses to form tiny water droplets which are the basis of clouds. This is due to adiabatic cooling.

What weather condition would lead you to believe that air is stable?

Clouds that are wide spread and have little vertical thickness compared with their horizontal dimension. Little to moderate precipitation if any

Describe the direction of cyclonic and anticyclonic flow in both the Northern and Southern hemispheres

Cyclonic Flow is counterclockwise in the Northern and Clockwise in the Southern and Anticyclonic flow is clockwise in North and counterclockwise in the south

Why is evaporation a cooling process?

During the process of evaporation, the higher temperature, faster moving molecules escape the surface, resulting in a lower average molecular motion (temperature)

a. When is relative humidity highest during a typical day? When is it the lowest? b. At what time of day would dew most likely form? c. Write a generalization relating changes in air temperature to changes in relative humidity

Early morning; Late at night or midday Early morning If air temperature increases,the relative humidity will fall and vice verse provided the moisture content in the air remains the same.

For surface low pressure to exist for an extended period, what condition must exist aloft?

In order for surface low pressure to exist for a reasonable period of time, compensation must occur aloft. Surface pressure would be maintained if divergence aloft occurs at a rate equal to the inflow below.

What advantage does weather radar have over a standard rain gauge?

Is able to tell when precipitin is more intense, and can measure rate and direction of storm movement

Explain the cause of the Asian monsoon. Which season is the rainy season? (Summer or winter)

Is caused by pressure differences that are generated by unequal heating of the Earth's surface and it occurs in the winter

Describe the expected winter temperatures in the north-central states when the polar jet stream is located over Central Florida?

It would result in a much colder winter as the polar jet stream would be pulling in more cool air.

What happens as ice melts to become liquid water?

Molecules are becoming excited and thus breaks the bonds they have between each other making them more free-roaming.

In what way are land and sea breezes similar to mountain and valley breezes?

Mountain and valley breezes form through a process similar to sea and land breezes. During the day, the sun heats up valley air rapidly. Convection causes it to rise, causing a valley breeze. At night, the process is reversed.

List three forces that combine to direct wind (horizontal airflow). which of these forces is responsible for generating wind?

Pressure Gradient Force, Coriolis Force, Friction; Pressure Gradient Force

Describe sleet and freezing rain. Why does freezing rain result on some occasions and sleet on others.

Sleet- solid form when raindrops freeze while falling through a layer of subfreezing air. Freezing Rain- Solid Produced when supercooled raindrops freeze on contact with solid objects

What are the 6 processes by which water changes from one state to another and indicate whether heat is absorbed or released in each case.

Solid to gas- Sublimation Absorbs, Solid to liquid- melting Absorbs, gas to solid- deposition liberates, gas to liquid- condensation liberates, liquid to solid- freezing liberates, liquid to gas- evaporation Absorbs

Briefly describe the Southern Oscillation and how it is related to El Nino and La Nina

Southern Oscillation is the seesaw pattern of atmospheric pressure between the eastern and western Pacific Ocean. the atmospheric pressure conditions corresponding to the periodic warming of El Nino and cooling of La Nina.

A southwest wind blows from the ________________ (direction) toward the ______________ (direction.

Southwest direction toward the North East

Explain how horizontal convergence aloft affects surface pressure

Surface air pressure rises when horizontal convergence aloft is greater than horizontal divergence at the surface

What is the primary driving force of surface-ocean currents?

Surface winds

In the idealized three-cell model of atmospheric circulation, most of the united states is situated in which belt of prevailing winds?

The Hadley Cells

How does a major La Nina event influence the hurricane season in North Atlantic?

The cooling of the water would lower the amount of "fuel" that hurricanes use to keep motion so there should be a decrease in hurricane activity during a La Nina event.

What is the Intertropical Convergence zone (ITCZ)?

The zone of general convergence between the Northern Hemisphere and Southern Hemisphere trade winds

Compare and contrast rain, drizzle, and mist

They are all liquids, but rain has the largest water drops, drizzle is in the middle and mist is the smallest.

What property of water causes large bodies of water to remain warmer than adjacent landmasses in winter but cooler in summer?

This relates to the property of water having a high heat capacity. Water heats up and cools down much slower than most common substances

Which winds are found between the equator and 30 degrees latitude?

Trade winds

Why is there a relatively high frequency of dense fog along the pacific coast?

Warm, moist air moves over the pacific ocean and the Pacific Ocean's surface is very cold thus causing the dense fog.

Describe how a major El Nino event tends to affect the weather in Peru and Chile as compared to Indonesia and Australia.

Weather becomes very wet in Peru and Chile thus causing major flooding. In Indonesia or Australia, the weather ends up being dryer thus leading to droughts and increased risk of forest fires

Describe how winds blow in relation to areas of high pressure and low pressure

Winds will move from areas of high pressure to lower pressure as an attempt to maintain some sort of equilibrium in the atmosphere

At what time of year should we expect the fastest polar jet streams? Explain.

Winter because of the stronger temperature gradient that exists in the middle latitudeslattitudes

Define Monsoon

a seasonal prevailing wind in the region of South and Southeast Asia, blowing from the southwest between May and September and bringing rain

Are regions that are dry throughout the year dominated by high or low pressure?

as high pressure is an area of sinking air, and air tends to dry out as it sinks, leaving sunny skies.

Explain how cities create their own local winds.

release of energy due to combustion and enhanced absorption of solar radiation in the cities by buildings and dark surfaces warms the air and enhances convection. The rising air is replaced by cooler air from the surrounding countryside

How does stable air differ from unstable air?

stable air- Air that resists vertical displacement, if lifted adiabatic cooling will cause its temperature to be lower than the surrounding environment. Unstable Air- Air that doesn't resist vertical displacement, if lifted temperature will not cool as rapidly as the surrounding environment

Describe conditional instability

the most common type of atmospheric instability, prevails when moist air has an environmental lapse rate between the dry and wet adiabatic rates. air must be lifted by some uplift mechanism before it reaches the level where it becomes unstable and rises on its own

Describe atmospheric pressure.

the pressure exerted by the weight of the atmosphere

Briefly summarize the collision-coalescence process

the process of cloud droplets increasing in size by colliding and coalescing. When droplets bump into each other, it is called collision, and when they stick together, it is called coalescence.

What is wind, and what generates it

wind is the result of horizontal differences in atmospheric pressure, The pressure gradient