Chapter 3 - Air Temperature

Radiation balance

Caused by shortwave radiation during the day, cooling at night

Temperature peak being mid-afternoon rather than noon

Caused by solar radiation surplus being run until sunset

Radiation inversion

Surface is colder than the air above the surface; caused by infrared radiation

Warmer air mixing with wind and air near surface

Causes warmth

Diurnal cycle

Daily temperature cycle (range is larger near the ground)

Small daily temperature range

Caused by clouds absorbing outgoing radiation and emitting it back down

Humid regions

Often have smaller diurnal range

Primary cause of nighttime cooling on Earth’s surface

Emission of infrared radiation from the surface

Wind condition where radiation inversion is strongest

Calm conditions (no wind)

Water vapor absorbing outgoing infrared radiation and re-emitting

Causes humid air to keep nighttime surface temperatures warmer

Thermal belt

Zone of relatively warm air found on hillside slopes above cold valleys during radiation inversion

Methods of protecting crops from cold night air

Cover, orchard heaters, wind machines, irrigation, icing it down

Icing down crops to protect them

Creates energy release throughout the night

Normal temperature

30-year average of high or low temperature

Controls of temperature variations from one place to another

Proximity to oceans, ocean currents, latitude, elevation

Extreme highest temperatures on Earth

Found in Dallol, Ethiopia

Extreme lowest temperatures on Earth

Found in interior of Siberia and Greenland + Antarctica

Heating degree day

65F - mean temperature = heating degree day

People begin to use heating indoors when average daily temperature drops below 65F

Cooling degree day

mean temperature - 65F = cooling degree day

People begin to use cooling indoors when average daily temperature is above 65F

Growing degree day

mean daily temperature 1F above base temp for a crop

Used by farmers as a guide to planting

Sensible temperature

Body’s perceived temperature

How we exchange heat with the environment

How wind increases rate of heat loss from the human body

Removes thin, insulating layer of warm air molecules located next to the skin

Wind Chill Index

Only defined for temperatures below 50F

Hypothermia

Body temperature drops below normal; often occurring between freezing and 50F

Cooperative Station thermometer

Placed in a shelter 2m above ground, painted white, must open North, no asphalt effect