Chapter 4 - Temperature Relations
CNN is reporting that a chunk of ice shelf nearly the size of Manhattan
has broken away from Ellesmere Island in Canada's northern Arctic. Just
last month 21 square miles of ice broke free from the Markham Ice
Shelf. Scientists are saying that Ellesmere Island has now lost more than
10 times the ice that was predicted earlier this summer.
Question of the Day
If the arctic ice cap melts completely,
Then, what do you think will be the worst
thing that will happen to the global
ecology?
Chapter 4 - Temperature Relations
Objectives:
1. List reasons why differences in
temperature exist on a microscale
2. Explain why organisms perform best in a
narrow range of temperature
3. Describe how organisms compensate for
variations in environmental temperatures
Chapter 4 - Temperature Relations
Objectives:
4. Define resting stages and their applications
5. Identify where heat comes from and where
is goes!!!
Temperature Microscales
Temperature Microscales
Cool
Hot
Fig. 4.3
Fig. 4.1
Temperature Microscales
1. Altitude: temperatures decrease as altitude
increases
2. Aspect: Shading parts of the land e.g., “North Facing Slope” and ski areas
Temperature Microscales
3. Vegetation: Plants create microclimate
Temperature Microscales
4. Color: e.g., ground
Coolest
Warmest
Solar Radiation
Temperature Microscales
5. Boulders, burrows, or any
other landscape feature that
absorbs, reflects, or alters
the sun’s radiant energy,
alters temperature.
Temperature Microscales
6. Aquatic habitats:
• Evaporation of water surfaces cools “Latent
heat of vaporization” - absorbs heat as it
evaporates
• Freezing “Latent heat of fusion” gives up
heat energy to the environment
• Thermal stability of water is greater than air
Fig. 4.7
What do we know so far?
1. Temperature can change dramatically over
a very small distance.
2. Organisms may cause this change (e.g.,
plant and shade).
3. Colors, and other landscape features drive
this change.
4. Aquatic Environments more resistant to
changes in temperature.
2nd Question of the Day!!
“Micro” infers a very small area. Define how
big this is (using a metric scale) defending
your answer with examples.
Temperature Effects
Range of Tolerance
Environmental range of biological processes:
Minimum Temperature 0C
Maximum Temperature 40 C
Optimum Temperature* 20-40 C
* different for each organism
Temperature Effects
Death at High Temperatures:
Primary cause is the denaturing of enzyme
proteins necessary for metabolism
Death at Low Temperatures:
Formation of ice crystals within cells,
rupturing membranes
Temperature Effects
Between the Extremes:
Temperature affects the organisms by
controlling the rates of enzyme reactions in
metabolic pathways!!
Fig. 4.10
Law of Tolerance
Shelford (1913)
“There are upper and lower bounds to
physical factors that an organism can
tolerate”
Law of Tolerance
Fig. 4.10
Adaptations Temp. Variations
Organisms must regulate temperature (if
possible) for optimum growth.
How?
They can gain or lose heat in a variety of ways
Physics of Energy Exchange
•
•
•
•
Radiation (Electromagnetic)
Conduction
Convection
Evaporation
Radiation
Transfer of energy through electromagnetism
• Every object emits radiation
• Amount and type depends on the
temperature of object
• Does not require the presence of matter
• Living organisms absorb solar radiation in
the visible light range, and radiate energy as
heat
Conduction
Movement of heat through matter
FROM: region of high temperature
TO:
region of low temperature
RATE: proportional to gradient
proportional to surface area
conductivity of material
inversely proportional to distance
Convection
Transfer of heat by the circulation of a fluid-liquid or gas
Wind Chill
Convection
Transfer of heat by the circulation of a fluid-liquid or gas
WC = 91.4 - (0.474677 0.020425 * V + 0.303107 *
SQRT(V)) * (91.4 - T)
where:
WC = wind chill index
V = wind speed (mph)
T = temperature (° F)
Evaporation
Heat energy dissipated by converting water
from liquid to gas:
e.g., sweat, evapotranspiration
539 kcal of heat consumed to covert one kg of
water from liquid to vapor
Latent Heat of Vaporization
Thermal Budgets
If: an organism absorbs more energy than it
emits or stores in chemical bonds
Then: Temperature increases
If: an organism absorbs less energy than it
emits or releases from chemical bonds
Then: Temperature decreases
Temperature - The Formula
Hs = Hm + Hcd + Hcv + Hr + He
Where:
Hs = Total heat stored in body
Hm= Heat gained from metabolism
Hcd = Heat gained or lost from conduction
Hcv = Heat gained or lost from convection
Temperature - The Formula
Hs = Hm + Hcd + Hcv + Hr + He
Where:
Hr = Heat gained or lost through
electromagnetic radiation
He = Heat lost through evaporation
Fig. 4.14
Thermal Regulation
How do organisms regulate temperature?
Have we answered this question?
Subject of lecture next Tuesday
What did we learn today?
• Microclimates
• Types of energy and heat transfer
• Minimum, maximum and optimum
temperatures
• Read Chapter 4 for next Tuesday-------Chapter 4
Temperature
Thermal inputs - Generating Heat!!:
Direct sunlight
Diffuse solar radiation
Heat radiation from surroundings
Conduction from environment
Heat of metabolism
Temperature
Thermal Outputs - Losing Heat!!!!:
Longwave radiation to surroundings
Conduction to environment
Convection
Evaporation