Chapter 3 Flashcards
Temperature
Represents the average kinetic energy of the air molecules
Meteorologists measure temperature at the same reference height, _________ aborve ground usually on a grass-covered surface
1.5 meters (5 feet)
Air temperatures at this 1.5-meter height are called ________________
surface temperatures
Surface temperature is the temperature of the air _______________, not the temperature of the ground itself
near the ground
When energy gains exceed losses, the temperature ______________
increases
Turbulence
Irregular air motions that mix heat and moisture from the surface higher up in the atmosphere
Isotherms
Lines of constant temperature that are oriented east-west over the Southern Hemisphere, where the surface is mostly ocean
Temperature gradient
A change of temperature divided by the distance over which the temperature change occurs.
Large temperature gradients exist where the isotherms are close together
In winter, when a polar region is in darkness, the middle latitude regions have large temperature gradients
Diurnal temperature cycle
The repeating pattern of daily temperatures
This cycle includes the maximum and minimum daily temperatures and the times of day that they usually occur
The maximum temperature occurs during mid to late afternoon
The minimum temperature is reached around dawn
Diurnal temperature range
The difference between the maximum and minimum temperatures of any given day
Daily mean temperature
Usually determined by averaging the maximum and minimum temperature for a 24-hour period or sometimes by averaging all 24 hourly temperature measurements
Seasonal or annual temperature cycle
The very regular cycle of temperature throughout the year
Monthly mean (monthly average) temperature
is calculated by adding the daily mean temperature for each day of the month and dividing by the number of days in the month
Annual average temperature
Simply the sum of the monthly mean temperatures divided by 12
Annual temperature range
The difference between the warmest and coldest monthly mean temperatures of a given geographic location
Difference between the highest and lowest daily temperature bserved in a given year or years
Major factors of energy imbalances
Latitude, surface type, elevation and aspect, relation to large bodies of water, advection, and cloud cover
The tilt of the Earth’s axis
the angle of inclination - affects the amount of incoming solar energy and is the reason for the seasonal cycle in temperature
The amount of incident solar energy at the top of the atmosphere, or ___________, is a function of time of the year, time of day, and latitude
insolation
The maximum temperature occurs after, or ________, the time of maximum solar input, which occurs in June on the summer solstice
lags
Latitude influences the annual temperature range because it affects the following:
- the seasonal variation of the insolation
- the solar zenith angle
- the length of day
The surface of the Earth absorbs approximately ________ of the solar energy incident at the top of the atmosphere
50%
Vegetation reduces the temperature range in several ways
Plants transpire and use some of the solar energy that reaches the surface
Evaporation in the vicinity of plants takes in energy that would otherwise go into the raising of temperature
At the higher elevation, the air _____________________
is less dense, and there are fewer molecules to absorb incoming solar radiation
_____________ is also an important influence on the energy budget of a region, particularly the solar energy side of the ledger
aspect
Aspect
Aspect is the direction that a mountain slope faces
In the Northern Hemisphere, under cloudless skies, a north-facing slope receives _____________ solar energy than a south-facing slope
less
* plants grow densely on the moister north-facing slopes
Large water bodies act to:
stabilize thermaly the temperature of the surrounding air so that the differences between months are reduced
The seasonal temperature cycle of a city is related to its proximitiy to a ______________
body of water
The factors that contribute to temperature differences between continental and maritime regions are as follows:
- The specific heat of water is almost three times greater than of land. More heat is therefore required to raise the temperature of water. Water also cools more slowly than land
- Evaporation of water reduces the teemperature extremes over and near lakes and oceans
- Solar radiation absorbed by water is distributed throughout a large depth of the water body as a result of mixing and the transparency of water to solar radiaiton. Over land, the solar radiaition is absorbed by the surface, and heat can quickly be transferred to the atmosphere above it
What explains London’s warmth in the winter?
Advection by the persistent southwesterly winds in winter that keep london warm
Clouds reflect solar radiation back ______________
into space
Clouds emit longwave radiation, which inhibits __________________
cooling of the air below
Cloud’s warming effect
They emit longwave radiation toward the surface
Normal temperatures
Temperatures averaged over a few decades
These climatological temperatures are computed by averaging all temperatures over a 3-year period
Anonalies
Departures for a given year are found by subtracting the normal value from that year’s mean value
Over the last 120 years, the average global surface temperature has increased approximately _______
0.6 degrees Celsius
1 degree F
El Niño
Causes unusualy warm waters over the eastern Pacific Ocean, and because the ocean affects the atmosphere, leads to warming temperatures across a sizble portion of the globe
La Niña
cools the Pacific and other parts of the globe
The energy losses usually exceed the energy gains by ____________
4:00 PM - when the maximum daily temperature is reached
Temperatures reach a minimum around ____________
sunrise
The dirunal temperature range is usually greater over regions ________________
far from large bodies of water
Cloud cover
Clouds reduce the temp range by minimizing the range between the daytime maximum and nighttime minimum temperatures
The factors affecting the diurnal temperature changes during a cycle are similar to those that determine the annual temperature cycle:
latitude
surface type
elevation and aspect
relationship to large bodies of water
cloud cover
Lapse rate
The change of temperature with height
continentality
hot summers and bitter winters far away from the moderating effects of an ocean
Most of the state-record highs and lows for states were actually set in the __________
1930’s
A rising parcel expands because ___________________
atmospheric pressure always decrease with altitude
As the parcel rises away from the ground, its potential energy increases. So the air molecules kinetic energy is being converted to _____________________
potential energy
A rising parcel of air always _________
cools
A dry parcel’s temperature will decrease by approximately ________ for each kilometer it rises
10 degrees celsisus
As the parcel descended, the potential energy of the molecules would be converted back to _________________
kinetic energy
A descending parcel of air always ____________
warms
Adiabactic process
A process in which no heat energy is gained or lost by the system in question
Dry adiabatic lapse rate
The 10 degree celsisus per kilometer rate of cooling resulting from expansion (rate of warming as a result of compression)
An air parcel that is warmer than the air around it is also less dense than the air around it - so the air will ________
rise
Environmental lapse rate
The specific change of temperature with altitude at any particular time and location
If the environmental lapse rate is larger than the dry adiabatic lapse rate, the parcel will ___________________________
remain warmer than its surroudings and keep rising
If the environmental lapse rate is smaller than the dry adiabatic lapse rate, the parcel will eventually reach the same temperature as its surroundings as it rises, __________________
and it will stop rising
Air that keeps rising because it is warmer than its surroundings is called ______________
statically unstable
When the environmental lapse rate is greater than 10 degrees Celsisus per kilometer, the atmosphere is said to be ___________________
absolutely unstable
*very favorable for strong upward motions of air because if a parcel of air is lifted upward, it will accelerate away from its original position
Statically stable atmosphere
Inhibits the vertical movements of air parcels
Regions of the atmosphere in which the temperature increases with altitude
Temperature inversions
A temperature inversion is an extreme case of a _______________
stable atmosphere
A temperature inversion that develops near the ground during the night is referred to as a ________________
nocturnal inversion => sometimes also called a radiation inversion
Temperature inversions often develop in _____________
valleys
Wind-chill temperature
Describes the increased loss of hear by the movement of the air
The win chill is relevant to humans and other animals that need to maintain a constant temperature that is higher than their surroudnings
Growing degree-days
A heat index that is related to plant development
Can be used to predict when a crop will reach maturity
Each day’s GDDs are calculated by subtracting a reference temperature, which varies with plant species, from the daily mean temperature, setting values less than zero to zero
heating degree-days (HDD)
used to estimate fuel-consumption needs
One heating degree-day is defined as each degree that the mean temperature is below 65 degrees F.
ex. 55 degrees equates to 10 heating-degree days
cooling degree-days
The amount of energy used to cool a building is related to the CDDs
