Chapter Three - Test One Flashcards
In order to examine the distribution of temp. on maps, we use:
Isotherms (Line of equal temperature) - lines indicating equal (iso) temperature (therms)
Latitude (which determines the amount of solar radiation received) is the major controller of temperature (as seen in Figure 2.9). There are however other controls:
- Differential heating of land and water
- Ocean currents
- Altitude
- Geographic Position
- Cloud Cover
Land surfaces heat more rapidly and to a higher temperature (daytime) and cool more rapidly and to a lower temp. (Night time) than do water surfaces (Fig. 3.3), because:
1) Water is mobile, land is not
2) Water is transparent, land is not
3) The Specific Heat [def: as the amount of heat needed to raise the temperature of 1 gram of a substance 1ºC] of water is 3 times greater that the specific heat of land
Land heats up __ times as much as water for a given amount of solar radiation striking the surface
3
Oceans act as regulators of temperature:
keeping coastal areas:
- Cooler during the day [summer], warmer during the night [winter] when compared to mid-continent locations.
Ocean Currents
Greatly influence temps. because of their ability to transport warm water towards the poles and cold water towards the equator
The Gulf Stream, with temp. between 75-85º keeps:
The Atlantic Coast States warmer in winter
The California Current, with temp. between 45o–55º keeps:
The Pacific Coast States cool in summer
Temperature generally decreases wrt
height in the troposphere; therefore…
Higher elevations tend to be colder
A location’s proximity to certain geographic features can also control temperatures:
Geographic Position
- Windward/leeward coast
Clouds, because they limit both incoming solar (reducing afternoon maxima) and outgoing terrestrial (reducing early morning minima):
- Reduce the amount of temperature variability
Greatest variability in the world is
Siberia
Isotherms indicate a decrease in temperature toward the ____
- Coldest and hottest locations found over \_\_\_\_ - Tropical latitudes experience very little annual \_\_\_\_ - Mid and high-latitude, continental areas experience very \_\_\_\_ annual variation - N. Hem. Experiences larger annual \_\_\_\_ than S. Hem
poles; land; variation; large; variation
On typical days:
After sunrise: solar radiation heats the earth’s surface –
After sunset: both the surface and the atmosphere lose heat (cool) by emitting long λ radiation thru a process called:
Which warms the first few inches of the air through conduction leading to convection and hence: Warming of the atmosphere, Additional heating occurs as the atmosphere captures Earth’s long λ radiation
Radiational cooling
Although incoming solar radiation is most intense at noon, the
maximum temperatures tend to occur considerably later:
Lag of the Maximum
Usually between 3-6 pm (fig 3.20)
This lag is due to the fact that:
- Incoming solar radiation still exceeds outgoing terrestrial radiation for several hours after noon
Temp. Will continue to rise, reaching a maximum when the:
Outgoing terrestrial radiation = the incoming solar radiation.
The temperature will begin to fall in the afternoon once: Outgoing terrestrial > incoming solar, reaching a min. well past midnight:
- Usually just before sunrise (fig 3.20)
Daily Temperature Changes
Influenced by several factors including:
- Coastal areas
- Clouds: clouds limits the change
- Water vapor: remember the atmospheric window
Annual Temperature Variations
The same reasoning can be used to examine the seasonal lag in
temperature which generally results in:
- January or February being the coldest months
- July or August being the warmest month
There are numerous types of thermometers (meter or measure of therms), operating on different physical principles, each with their
own advantages and disadvantages.
They only infer the “average speed” of air’s molecules
Mechanical Thermometers
Most substances contract when cooled and expand when heated.
This attribute is used by:
Liquid-in-glass thermometers (Fig. 3.21)
- Mercury (freezing point 37 or 38 degrees)
- Alcohol
Bimetal Strip
- used in thermographs (fig 3.23)
Electrical Thermometers
The flow of electricity is temperature dependent
Thermisters (thermal resisters) (Fig. 3.24)
- Used on radiosondes because they’re very light
Radiometers
Sensors that measure infrared radiation, which as we saw earlier is dependent on temperature (Stephan-Boltzmann Law)
- Used on satellites
The lowest temperature possible (theoretically) is that at which all atoms/molecules stop moving:
Absolute Zero (AZ) At AZ we start a temperature scale called the: Kelvin Scale (K)
Kelvin is convenient for scientific computations
because it is never negative; however,
non-scientist generally use either:
- Celsius (ºC) (also called Centigrade)
- Fahrenheit (ºF)
At AZ, the temperature is equal to:
0 k and -273ºC and -459ºF
- Fahrenheit (ºF)
One K degree = one C degree = ??
1.8 F degrees
Celsius and Fahrenheit are equal at -40.0
HDD =
65ºF – (Daily Mean Temperature)
CDD =
(daily Mean Temperature) – 65ºF
Heating Degree Days (HDD) and Cooling Degree Days (CDD)
Based on the assumption that people will turn on their furnaces (ac) when the Daily Mean Temperature (DMT) drops below (rises above) 65ºF
Growing Degree Days (GDD)
Not to be outdone, farmers have developed GDD units to guide for planting/maturation/harvest of crops.
- The GDD are Crop Specific
Wind Chill Temperature (WCT) (Box 3.5)
Developed (updated in 2001) by scientists using a combination of:
- Wind speed (V)
- Temperature (T)
Determine air’s ability to remove heat from human bodies (Figs. 3.H).
WCT = 35.74 + 0.6215 (T) – 35.75(V^0.16) + 0.4275(T)(V^0.16)
