ATMS 120 UIUC Exam 1 Guide
With Complete Solution
Top of the earth's atmosphere - ANSWER toa = 120 km (75 miles)
99.9% below 36 miles
Air density and height - ANSWER air density decreases rapidly with height
Primary gasses in earth's atmosphere - ANSWER water vapor
nitrogen - most abundant (78%)
methane
ozone
carbon dioxide
oxygen - 2nd most abundant (21%)
Argon - almost all of last 1%
How does the earth keep warm - ANSWER 1. all gasses are almost completely
transparent to sun's peak energy output (visible light)
2. O2/N2 are also transparent to earth's peak energy output (thermal
infrared energy), but greenhouse gasses are not, so they efficiently absorb
this energy/warm the atmosphere
Average global surface air temperature without greenhouse gasses -
ANSWER 0 degrees F
,Average global surface air temperature with greenhouse gasses - ANSWER
59 degrees F
Difference between weather and climate - ANSWER weather is highly variable
day-to-day/"normal" for temperature to be 15 degrees F above/below
average temperature
climate is the average of weather (typically a 30 year average)
When are records for weather/climate set? - ANSWER when temperatures are
4+ standard deviations away from mean
Definition of temperature - ANSWER a measure of the average speed (kinetic
energy) of all the molecules in a substance (solid, liquid, gas)
Relationship between temperature/density - ANSWER higher the air
temperature, the faster the air molecules move
faster the molecules move, the more space they will need to move around
warming the air will cause it to expand
cooling the air will cause it to contract
so warm air is less dense than cold air
What causes temperature variations? - ANSWER 1. the angle of the sun's
rays/length of daylight hours are not constant
2. the earth is covered with many different surface types that absorb energy
differently
Summer solstice - ANSWER june 21st
sun's rays are direct on tropic of cancer
,most daylight hours
Autumnal equinox - ANSWER september 21st
sun's rays are direct on equator
12 hours daylight/12 hours night
Winter solstice - ANSWER december 21st
sun's rays direct on tropic of capricorn
least daylight hours
Vernal equinox - ANSWER march 21st
sun's rays are direct on equator
12 hours daylight/12 hours night
What causes seasonal variations in temperature? - ANSWER the tilt of the
earth on its axis causes the sun's rays to become more (or less) direct which
concentrates (or disperses) the sun's energy throughout the year
Latitude/temperature variation - ANSWER the greater the latitude, the
greater the yearly variation in temperature
winter - low sun angle, fewer daylight hours, sun's path through atmosphere
is long
summer - high sun angle, more daylight hours, sun's path through the
atmosphere is short
Temperature inversion - ANSWER any layer of the atmosphere where the
temperature increases with height
, What layer of the atmosphere does weather occur in? - ANSWER troposphere
80% of the atmosphere mass is in the troposphere
Pressure - ANSWER force per unit area applied by the air (mb)
equivalent to weight of the air in a column over an area (like a square inch)
Average sea level pressure - ANSWER 1013.25 mb = 14.7 lbs/in2 = 29.92 in
hg
high sfc pressure = 1045 mb
low sfc pressure = 980 mb
pressure decreases rapidly with height, balanced by gravity
Low surface pressure weather - ANSWER at pressure less than 1000 mb
clouds, precipitation, unsettled weather
High surface pressure weather - ANSWER at pressure greater than 1000 mb
fair weather (nice)
Pressure variations - ANSWER air moves because of horizontal pressure
differences
always moves from higher pressure to lower pressure
the greater the change in pressure over a given distance, the faster the wind
Latent heat - ANSWER heat associated with phase change (water changing
form between gas, liquid, solid)
can't see water vapor
Gas - ANSWER highest energy state of water
With Complete Solution
Top of the earth's atmosphere - ANSWER toa = 120 km (75 miles)
99.9% below 36 miles
Air density and height - ANSWER air density decreases rapidly with height
Primary gasses in earth's atmosphere - ANSWER water vapor
nitrogen - most abundant (78%)
methane
ozone
carbon dioxide
oxygen - 2nd most abundant (21%)
Argon - almost all of last 1%
How does the earth keep warm - ANSWER 1. all gasses are almost completely
transparent to sun's peak energy output (visible light)
2. O2/N2 are also transparent to earth's peak energy output (thermal
infrared energy), but greenhouse gasses are not, so they efficiently absorb
this energy/warm the atmosphere
Average global surface air temperature without greenhouse gasses -
ANSWER 0 degrees F
,Average global surface air temperature with greenhouse gasses - ANSWER
59 degrees F
Difference between weather and climate - ANSWER weather is highly variable
day-to-day/"normal" for temperature to be 15 degrees F above/below
average temperature
climate is the average of weather (typically a 30 year average)
When are records for weather/climate set? - ANSWER when temperatures are
4+ standard deviations away from mean
Definition of temperature - ANSWER a measure of the average speed (kinetic
energy) of all the molecules in a substance (solid, liquid, gas)
Relationship between temperature/density - ANSWER higher the air
temperature, the faster the air molecules move
faster the molecules move, the more space they will need to move around
warming the air will cause it to expand
cooling the air will cause it to contract
so warm air is less dense than cold air
What causes temperature variations? - ANSWER 1. the angle of the sun's
rays/length of daylight hours are not constant
2. the earth is covered with many different surface types that absorb energy
differently
Summer solstice - ANSWER june 21st
sun's rays are direct on tropic of cancer
,most daylight hours
Autumnal equinox - ANSWER september 21st
sun's rays are direct on equator
12 hours daylight/12 hours night
Winter solstice - ANSWER december 21st
sun's rays direct on tropic of capricorn
least daylight hours
Vernal equinox - ANSWER march 21st
sun's rays are direct on equator
12 hours daylight/12 hours night
What causes seasonal variations in temperature? - ANSWER the tilt of the
earth on its axis causes the sun's rays to become more (or less) direct which
concentrates (or disperses) the sun's energy throughout the year
Latitude/temperature variation - ANSWER the greater the latitude, the
greater the yearly variation in temperature
winter - low sun angle, fewer daylight hours, sun's path through atmosphere
is long
summer - high sun angle, more daylight hours, sun's path through the
atmosphere is short
Temperature inversion - ANSWER any layer of the atmosphere where the
temperature increases with height
, What layer of the atmosphere does weather occur in? - ANSWER troposphere
80% of the atmosphere mass is in the troposphere
Pressure - ANSWER force per unit area applied by the air (mb)
equivalent to weight of the air in a column over an area (like a square inch)
Average sea level pressure - ANSWER 1013.25 mb = 14.7 lbs/in2 = 29.92 in
hg
high sfc pressure = 1045 mb
low sfc pressure = 980 mb
pressure decreases rapidly with height, balanced by gravity
Low surface pressure weather - ANSWER at pressure less than 1000 mb
clouds, precipitation, unsettled weather
High surface pressure weather - ANSWER at pressure greater than 1000 mb
fair weather (nice)
Pressure variations - ANSWER air moves because of horizontal pressure
differences
always moves from higher pressure to lower pressure
the greater the change in pressure over a given distance, the faster the wind
Latent heat - ANSWER heat associated with phase change (water changing
form between gas, liquid, solid)
can't see water vapor
Gas - ANSWER highest energy state of water
