Temperature and Heat Flashcards
what is temperature?
- a measure of the average velocity of molecules
- a measure of the potential heat exchange between objects
what is the molecular motion for solids, liquids, and gases/space
solids - vibration
liquids - rotation
translation - free movement through space
the higher the temp, the more/less heat being exchanged between objects
more
what is heat?
- form of energy capable of being transferred between systems
- the total molecular motion of a substance
what are the heat transfer mechanisms?
conduction - solids
convection - liquids, gases
radiation - needs no medium
What are the temperature scales
- Fahrenheit
32° = freezing
212° = boiling - Celsius
0° = freezing
100° = boiling - Kelvin
0 means absolute zero
How to find temp stats - daily mean, daily range, monthly mean, yearly mean, annual range
- daily mean = (min+max)/2
- daily range = high - low
- monthly mean = average of daily means
- yearly mean = average of monthly means
- annual range = mean of warmest - coldest month
What are first-order weather stations and how do we fill in the gaps?
- stations that are monitored 24/7 by trained, certified observers (about 270 in US)
- fill in the gaps with Cooperative Observer Program (COOP)
What are daily temperature cycles governed by and when do the daily highs and lows occur?
- governed by radiation cycles, clouds, moisture, transient air masses
- daily low usually near sunrise
- daily high usually mid afternoon
What is the Environmental Temperature Lapse Rate (ELR)?
the average lapse rate (6.4°C/1000m)
why is it cooler at night?
- lower atmospheric pressure
- gases expand at lower temps
- as gas expands, molecules and atoms within it more slowly
- since air temp is just a measure of how fast the molecules in air are moving, the rate of motion is lower - heating takes place at the bottom of the troposphere
what is a temperature inversion?
when temperature increases with height
- usually returns to lapse rate after a few hundred feet
what causes temperature inversions?
- normal radiational cooling (on a calm, clear night)
- cold air drainage
-synoptic conditions
what are synoptic conditions?
the large-scale, general weather patterns and atmospheric conditions over a region
what is the issue with temperature inversions? two examples
- pollution can be trapped
- Great London Smog and Donora, PA
How does climate change impact temperature inversions?
by altering temperature patterns, circulation, and the frequency of extreme weather events
what is Q*?
net radiation
Why is there differential heating of land and water? Which cools faster?
- land warms/cools more rapidly than water
- land is opaque, no mixing between layers, lower specific heat, and most of the net radiation is used for sensible heat
- ocean is transparent, there is mixing between layers, higher specific heat, most net radiation used for latent heat transfer
what is latent heat?
energy gained or lost when a substance changes from one state to another (e.g. when a pot of water is kept boiling, the temperature remains at 100 °C (212 °F) until the last drop evaporates, because all the heat being added to the liquid is absorbed as latent heat of vaporization and carried away by the escaping vapor molecules)
what is specific heat?
the heat capacity of a substance
- specific heat of water is 5x greater than land’s
what is sensible heat?
the heat that causes a change in temp of a substance but does not change its phase (e.g. warms water, doesn’t melt ice)
