Temperature and Heat

Question 1

what is temperature?

Answer 1

• a measure of the average velocity of molecules
• a measure of the potential heat exchange between objects

Question 2

what is the molecular motion for solids, liquids, and gases/space

Answer 2

solids - vibration
liquids - rotation
translation - free movement through space

Question 3

the higher the temp, the more/less heat being exchanged between objects

Answer 3

more

Question 4

what is heat?

Answer 4

• form of energy capable of being transferred between systems
• the total molecular motion of a substance

Question 5

what are the heat transfer mechanisms?

Answer 5

conduction - solids
convection - liquids, gases
radiation - needs no medium

Question 6

What are the temperature scales

Answer 6

• Fahrenheit
  32° = freezing
  212° = boiling
• Celsius
  0° = freezing
  100° = boiling
• Kelvin
  0 means absolute zero

Question 7

How to find temp stats - daily mean, daily range, monthly mean, yearly mean, annual range

Answer 7

• 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

Question 8

What are first-order weather stations and how do we fill in the gaps?

Answer 8

• stations that are monitored 24/7 by trained, certified observers (about 270 in US)
• fill in the gaps with Cooperative Observer Program (COOP)

Question 9

What are daily temperature cycles governed by and when do the daily highs and lows occur?

Answer 9

• governed by radiation cycles, clouds, moisture, transient air masses
• daily low usually near sunrise
• daily high usually mid afternoon

Question 10

What is the Environmental Temperature Lapse Rate (ELR)?

Answer 10

the average lapse rate (6.4°C/1000m)

Question 11

why is it cooler at night?

Answer 11

1. 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
2. heating takes place at the bottom of the troposphere

Question 12

what is a temperature inversion?

Answer 12

when temperature increases with height
- usually returns to lapse rate after a few hundred feet

Question 13

what causes temperature inversions?

Answer 13

• normal radiational cooling (on a calm, clear night)
• cold air drainage
  -synoptic conditions

Question 14

what are synoptic conditions?

Answer 14

the large-scale, general weather patterns and atmospheric conditions over a region

Question 15

what is the issue with temperature inversions? two examples

Answer 15

• pollution can be trapped
• Great London Smog and Donora, PA

Question 15

How does climate change impact temperature inversions?

Answer 15

by altering temperature patterns, circulation, and the frequency of extreme weather events

Question 15

what is Q*?

Answer 15

net radiation

Question 15

Why is there differential heating of land and water? Which cools faster?

Answer 15

• 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

Question 16

what is latent heat?

Answer 16

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)

Question 17

what is specific heat?

Answer 17

the heat capacity of a substance
- specific heat of water is 5x greater than land’s

Question 18

what is sensible heat?

Answer 18

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)