A&O SCI 1 Lecture 2: Heat & Radiation Lecture
8 Jun 2018
School
Department
Course
Professor
Heat and Radiation
Lecture Outline:
I. Temperature
II. Energy Transfer
III. Radiation
IV. The Scientific Method
TEMPERATURE
• Temperature is a measure of the internal heat energy of a substance
• The molecules that make up all matter are in constant motion
• By "internal heat energy," we really means this random molecular motion
• Molecular motion (translation, rotation, vibration) is therefore the reason any substance has a
temperature
• The more the molecules that make up a substance move, the higher its temperature
3 scales: Fahrenheit, Celsius, Kelvin
A few words about geography
• A location on earth is specified by latitude and longitude
• Latitude is particularly relevant to climate, as we will see
• Climate scientists speak of four latitude zones
a. Tropics (20S and 20N)
b. Subtropics (20N-35N and 20S-35S)
c. Mid-Latitudes (35N-60N) and 35S-60S)
d. High-latitudes (60N-90N and 60S-90S)
• For references
o Hawaii 21N
o LA: 34N
o Anchorage: 61N
The pillars of science: observation and theory
• The idea that truth can be derives from observing the natural world was revolutionary when it was
first proposed nearly 500 years ago
• Careful observation and measurement is one of the two pillars of science
• The other pillar of science is theory, expressed in mathematics
• Using observation; key characteristic of climate: temperature
Key Features of the planet's temperature distribution
• The tropics are generally about 40 Celsius (70F) warmer than the high latitudes
• Temperature patterns vary seasonally
• In the tropics the seasonal variation is small, and marked by a north-south movement of the
maximum
• In the mid- to high- latitudes, the seasonal variation are much greater
• In the northern hemisphere, seasonal variation is greater than in the southern hemisphere
• Over the ocean the season variation is much smaller than on land
ENERGY TRANSFER
Means by which energy is transferred
1. Conduction
2. Phase changes
3. Convection
4. Radiation
Conduction
• Fast moving molecules of Substance 1 collide with neighboring molecules of Substance 2, which
are moving more slowly
• This forces the molecules of Sub2 to speed up
• Sub2 becomes hotter as a result of its physical contact with Sub1
• This form of heat transfer often occurs between the atmosphere and the earth's surface and is
also known as sensible heat flux
Sensible heat flux is measured in power per unit area, or W/m2
• Positive (red colors): flux is from surface to atmosphere
• Negative (blue colors): flux is from atmosphere to surface
Key features of planet's Sensible heat Flux distribution
Document Summary
A few words about geography: a location on earth is specified by latitude and longitude. Latitude is particularly relevant to climate, as we will see: climate scientists speak of four latitude zones, tropics (20s and 20n, subtropics (20n-35n and 20s-35s, mid-latitudes (35n-60n) and 35s-60s, high-latitudes (60n-90n and 60s-90s) For references: hawaii 21n, la: 34n, anchorage: 61n. Key features of the planet"s temperature distribution: the tropics are generally about 40 celsius (70f) warmer than the high latitudes, temperature patterns vary seasonally. In the tropics the seasonal variation is small, and marked by a north-south movement of the maximum. In the mid- to high- latitudes, the seasonal variation are much greater. In the northern hemisphere, seasonal variation is greater than in the southern hemisphere: over the ocean the season variation is much smaller than on land. Means by which energy is transferred: conduction, phase changes, convection, radiation.
