Meteorology 106


Temperature is:
Eight controls on atmospheric temperature

1) Amount of Insolation

The more insolation absorbed - the higher the energy, the higher the temperature
Amount received is controlled by the exposure time and angle of insolation.

2) Exposure Time

Daily variation
Seasonal Variation

3) Angle of Insolation

Daily Variation
At sunrise the angle at which the sun's rays strike the Earth's surface are very low.
Lower intensity radiation
At noon the angle is much higher
Greater intensity radiation

Latitude Variation
During an Equinox, the subsolar point is at the Equator
The intensity of solar radiation is 100% at that point.
North or south the sun's rays strike the Earth at an angle, thus decreasing the angle at which the rays strike the surface.

Seasonal Variation
Northern hemisphere:
Wintertime the sun is low in the southern sky
A lower insolation angle means lower intensity of radiation received at the surface.
Summertime the sun is much higher in the sky - higher insolation angle means more intense radiation at the surface.

Land vs. Water

Coastal areas are generally cooler than inland areas and show lower annual and daily variations in temperature
Four thermal properties of water and land

4) Four Thermal Properties

A. Penetration
Insolation is able to penetrate water - the energy is distributed throughout a thick column of water
Insolation is absorbed at the surface of the land and is unable to penetrate beneath the surface

B. Specific Heat
The amount of energy required to raise the temperature 1° Celsius.
It requires 5 times more energy to raise the temperature of water one degree than it takes to raise the temperature of rock one degree.

C. Convection
The movement of material due to heat and gravity
Water is able to convect thus distributing the energy received
Rock can only transfer energy through conduction and radiation

D. Evaporation
Removes heat from the surface where evaporation takes place
Open water can readily evaporate thus cooling the water.
Land can also have heat removed due to evaporation, but is limited by the availability of water

Inland areas:
Coastal areas:

5) Ocean Currents

Circulating warm and cold ocean currents, driven by the wind.
Moderates and controls temperatures along coastal zones.
Transports heat to the polar regions.

6) Altitude

Temperature drops with increases in elevation (pressure and density also decrease)
Lapse Rate?
Insolation intensity increases
Rapid daytime heating and nighttime cooling.
High elevations location tend to show greater daily temperature ranges.

7) Geographic Position

Coastal vs. Inland location
Windward vs. Leeward location
Mountain Barriers

8) Cloud/Ground Cover: Albedo

Clear sky days are:
Clear sky nights are:
Impact of cloud cover on annual temperatures.
The air above dark surfaces will be:
The air above light surfaces will be:

Temperature Measurements

Thermometers: Measure temperature through the use of a liquid or metal that is sensitive to temperature

Types of Thermometers

Mercury thermometers - used for scientific thermometers
Alcohol thermometers - used in household thermometers
Spring Coil thermometers - uses a spring of metal; as the metal gets warm it expands.
Thermistors - Electronic thermometers that measure the changes in resistance of an electrical current as the temperature changes
Infrared Detectors (CCD) - electronically measure the amount of infrared radiation emitted by an object

Temperature Scales

Daniel Gabriel Fahrenheit - °F (1717)

Originally based on:
water freezes at:
water boils at:

Anders Celsius - °C (1742)

International System of Units (SI)- scientific measurements are all made in Celsius (Metric System)
water freezes at:
water boils at:

Absolute Temperature Scales

Based on the concept of Absolute Zero
Atoms are always in motion - moving or vibrating due to the amount of thermal energy they have
Absolute Zero is:
Absolute Temp. Scale: