The Earths Energy Balance

The Earths Energy Balance 1. Unequal Heating of the Atmosphere • The Earth does not heat evenly because of differences in latitude and seasons. • The amount of insolation (incoming solar radiation) varies: • More direct rays = more heat (equator). • Oblique angles = less heat (poles). 2. Latitude and Temperature • Temperature decreases as latitude increases (from equator to poles). • Equator: Sun’s rays strike directly → shorter distance, small area → hotter. • Poles: Sun’s rays hit at angle → longer distance, spread over large area → cooler. Heat zones: • Tropical (near equator) • Subtropical • Temperate • Polar (near poles) 3. Seasons (Caused by Tilt and Revolution) • Earth is tilted 23.5° from vertical and revolves around the sun. • Causes variation in temperature, day/night length, and seasonal changes: • Equinox (21 March & 21 September): equal day/night. • Summer Solstice (21 Dec): long days, short nights. • Winter Solstice (21 June): short days, long nights. • Southern Hemisphere: When it’s summer, it’s winter in the north (and vice versa). 4. Insolation • Insolation = solar radiation reaching the Earth. • Highest at the equator due to direct angle and smaller area. • Lower at the poles due to indirect angle and thicker atmosphere. • Affects climate zones and atmospheric pressure. 5. Atmospheric Pressure Basics • Atmospheric pressure is the force exerted by the weight of air molecules. • Measured in hectopascals (hPa) using a barometer. • Pressure decreases as altitude increases (approx. 10 hPa per 100 m). • Warm air = lower pressure (rises). • Cold air = higher pressure (sinks). 6. High vs Low Pressure Systems • High Pressure (H): • Air sinks. • Clear skies, no clouds or rain. • Stable conditions. • Air moves clockwise (Southern Hemisphere). • Low Pressure (L): • Air rises. • Cloudy, rainy, unstable conditions. • Air moves anti-clockwise (Southern Hemisphere). • Wind moves from High → Low Pressure. 7. Transfer of Energy • Energy is transferred from equator → poles to balance temperatures. • Two key methods: • Ocean currents: warm currents flow from equator to poles, cold from poles to equator. • Winds: caused by pressure differences; help move heat around the globe.