Meteorology Test 1

Question Answer
Solid to Liquid melting- absorbs heat
Liquid to Solid freezing- release heat
liquid to gas evaporation- absorbs heat
gas to liquid condensation- release heat
solid to gas sublimation- absorb heat
gas to solid deposition- release heat
solid to liquid to gas – Does this phase change absorb or release heat? absorbs
gas to liquid to gas – Does this phase change absorb or release heat? releases
if there's so much water vapor in the air that water won't evaporate saturation
what factors determine whether air is saturated? temperature and the amount of water in the atmosphere
the percentage of water vapor that is in the air relative to the temperature relative humidity- The amount of water vapor it takes for the air to be saturated depends on the temperature.The percentage of this amount that’s actually in the air is called the relative humidity.
the temperature at which the air would become saturated Dew point – if the temperature is below 0 degrees C or 32 degrees F than it is considered a frost point
How does relative humidity vary with the amount of water vapor in the air already and the temperature? adding water vapor and lowering the temperature will increase the relative humidity – removing water vapor and raising the temperature will decrease the relative humidity
gas cooling due to expansion adiabatic cooling
What is the dry adiabatic rate? unsaturated air cools at a rate of about 10 degrees C for every 1000 meters it rises
what is the wet adiabatic rate? Saturated air cools at a rate that varies about 5-9 degrees C per 1000 meters it rises
why is the wet adiabatic rate less than the dry adiabatic rate? when saturated air cools adiabatically, water vapor will start to condense, slowly releasing heat. This heat causes the air to cool more slowly
Name the four lifting process. Frontal wedging, Orographic lifting, Localized convective lifting, Convergence (FOLC)
Describe orographic lifting. air is forced up as it is blown into mountains – rising air is associated with precipitation and so it rains on the windward side of the mountain range – the leeward side can become a "rain shadow desert"
Describe frontal wedging. Front- a boundary between 2 different air masses- often warmer than the other – the warmer air mass is lifted by frontal weding
Describe Convergence. when air gets forced together – when this occurs, air has to go somewhere, so the air goes up – Ex. when air is flowing over water encounters land (convergent plate boundary) tends to slow down due to the rougher terrain and then the air piles up and rise
Describe Localized convective lifting. when unequal heating of the surface causes air to rise in places – such rising air parcels are sometimes called "thermals"
Uplifted air that tends to come back down stable air
air that is uplifted tends to keep rising unstable air
stable for dry and wet air absolutely stable
unstable for dry and wet air absolutely unstable
stable for dry air, unstable for wet air conditionally unstable
Why is rising air associated with precipitation? When air rises it cools. If it cools past its dew point, cloud formation can begin. This is the basis for precipitation.
Why is stability important when considering precipitation and storms? Storms require unstable air (air to rise and condense to form clouds)
Tiny particles in the atmosphere on which water can condense condensation nuclei
Name some things that can be condensation nuclei. dust, smoke, sea salt crystals, volcanic ash
Given a cloud name be able to describe it. cirro- very high cloudsalto- somewhat high cloudscumulo- puffy cloudsstrato- broad sheet or layer of cloudsnimbo- rain clouds
Higher atmosphere clouds are not formed from water droplets. What are they formed from and why? ice crystals – because higher in the atmosphere is colder and reaches the frost point (below 32 degrees F)
Explain the Bergeron process. Ice (since it is colder) has a lower saturation level and therefore the supercooled water droplets are attracted to the ice crystals – the ice crystals then grow until they are too big for the cloud to hold and then fall as ice crystals
How is rain formed? if the ice crystals melt on the way down from the cloud
How if snow formed? If the ice crystals stay ice crystals on the way down from the cloud
How is sleet formed? requires a warm layer of air above a cold layer of air. Falling ice crystals melt in warm layer then refreeze in the cold layer below and result in small ice pellets
How is freezing rain formed? Same conditions as sleet, but cold layer at bottom is thinner. Instead of refreezing, the raindrops are supercooled water that, when they hit the ground, freeze on impact
How is hail formed? require strong updraft and cumulonimbus clouds-start as small ice pellets that grow by colliding with supercooled water drops-repeated updrafts cause hail to make several trips up and down leading to a layered hailstone- falls when too big to be updrafted
What is meant by air pressure? air pressure is molecules that are constantly colliding with surfaces
What is the air pressure at sea level? 14.7 lbs/square in.
a scientific device that measure air pressure barometer
How does a mercury barometer work? The air pressure pushes down on the mercury which pushes it up
What are isobars? curves alone which pressure is constant
True or False: Air pressures in weather reports and weather maps are adjusted to sea level. True- Pressures in weather forecasts are adjusted to sea level. That is, when a weather map says 1020 mb in Sioux City, the actual reading on a barometer would be less than that.
how fast the pressure varies from place to place pressure gradient
How does the pressure gradient force affect wind? PGF always blows from high pressure to low pressure
How does the coriolis force affect wind? What causes the coriolis force? The coriolis force causes wind to veer to the right in the northern hemisphere and veer left in the souther hemisphere – caused by the rotation of earth on its axis
What forces affect air movement? coriolis force (always to the right of wind) and the pressure gradient force (always from high to low) – causes air to blow parallel to isobars with low pressure on the left of the wind – also PGF and coriolis forces cancel out
How can wind speed and direction be estimated from the pattern of isobars both near the surface and in the upper atmosphere? good fricken question… direction- parallel to isobars with low pressure to left, slightly to the right because the coriolis force and the stronger the pressure gradient force the quicker the wind speed
What is a cyclone, how does air move around it, and what weather is associated with a cyclone? a cyclone is a low pressure center with air revolving counterclockwise around it – air converges forcing air up and rising air is associated with rain
What is an anticyclone, how does air move around it, and what weather is associated with an anticyclone? an anticylone is a high pressure center with air revolving clockwise around it – air spreads out and results in clear skies
What is the basic pattern of global air circulation? Convection currents cause air to rise at the equator and sink at the poles
Global circulation continued- What are trade winds? a wind blowing steadily toward the equator from the northeast in the northern hemisphere or the southeast in the southern hemisphere, especially at sea level. Winds blow from the tropics (high pressure) to the equator (low pressure)
Global circulation continued- What are westerlies? Winds in both the northern and southern hemispheres tend to blow from west to east at mid-latitudes
Global circulation continued- What are polar easterlies? dry, cold prevailing winds that blow from the high-pressure areas of the poles towards the low pressure areas of the mid latitudes. Blow from the east.
Why does rain fall at the equator? Air rises at the equator and rising air is associated with rainfall
Why is it dry in many places around 25-30 degrees latitude? Air descends around 30 degrees latitude and sinking air (stable air) is associated with clear skies

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