Air Temperature Temperature a measure of the average

►Temperature : § a measure of the average speed at which molecules are moving

►Air temperature § the rate of motion of gas molecules in the atmosphere as

Temperature scales ► Celsius § water freezes at 0 o § water boils at

Conversions F = (1. 8 x o. C) + 32 ►o C = 0.

What determines the temperature of a place? 1. Insolation (daily and annual cycles) 2.

1. Insolation A. Changing angle of noon sun throughout the year changes temperature on

►Why temperature difference between equinoxes?

Spring : at end of cold, short day period ► § more energy loss

1. Insolation B. Changing angle of sun throughout the day changes temperature on a

►lag between max insolation and max temperature § because highest temp at time of

2. Latitude ► Higher latitudes receive less insolation than lower latitudes § sun’s rays

3. Urban/rural Surface ► Evapotranspiration differences ► Urban impervious surfaces ► Urban highly absorbent

4. Coastal vs. interior locations ►Water bodies have a moderating effect on temperature.

► “Land heats up and cools down more rapidly than water. ” § Therefore:

►Lake effect in Duluth is an example of changes in temperature due to being

5. Altitude / Elevation ►Temperature decreases as elevation increases. § less mass, less pressure,

►Conditions favorable for a temperature inversion: § cool, clear, calm night

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Air Temperature

►Temperature : § a measure of the average speed at which molecules are moving or vibrating.

►Air temperature § the rate of motion of gas molecules in the atmosphere as a result of the absorption of energy § measured by a thermometer

Temperature scales ► Celsius § water freezes at 0 o § water boils at 100 o ► Fahrenheit § water freezes at 32 o § water boils at 212 o ► Kelvin § no molecular motion at 0 K § water freezes at 273 K § water boils at 373 K

Conversions F = (1. 8 x o. C) + 32 ►o C = 0. 56 (o. F - 32) ►o ►K = o. C + 273

What determines the temperature of a place? 1. Insolation (daily and annual cycles) 2. Latitude 3. Urban/Rural Surface 4. Coastal vs. Interior location 5. Elevation

1. Insolation A. Changing angle of noon sun throughout the year changes temperature on a seasonal basis.

►Why temperature difference between equinoxes?

Spring : at end of cold, short day period ► § more energy loss ►Autumn : at end of day period § more energy gain warm, long

1. Insolation B. Changing angle of sun throughout the day changes temperature on a daily basis.

►lag between max insolation and max temperature § because highest temp at time of max ABSORBED insolation

2. Latitude ► Higher latitudes receive less insolation than lower latitudes § sun’s rays are more oblique § daylength is variable § Net energy surplus in tropics; net energy deficit in polar regions

3. Urban/rural Surface ► Evapotranspiration differences ► Urban impervious surfaces ► Urban highly absorbent (low albedo) surfaces ► Urban fuel consumption and excess heat ► “Urban heat island”

4. Coastal vs. interior locations ►Water bodies have a moderating effect on temperature.

► “Land heats up and cools down more rapidly than water. ” § Therefore: ►Coastal: smaller temperature ranges than continental locations. ►Coastal locations have their maximum temperatures well after maximum insolation.

►Lake effect in Duluth is an example of changes in temperature due to being close to a large body of water.

5. Altitude / Elevation ►Temperature decreases as elevation increases. § less mass, less pressure, less absorption

Exception: temperature inversion

►Conditions favorable for a temperature inversion: § cool, clear, calm night