EVOLUTION OF: THE EARTH’S ATMOSPHERE

andTHE CHEMISTRY

OF EARTH’S OCEANS

PART 1

Greenhouse effect occurs when certain gases, particularly carbon dioxide,methane and water vapor warm the surface of the planet. Light enters easilybut the gases intercept the infrared rays that the planet reflects and reradiates much of this energy toward the surface. This raises the temperature ~35°Cabove what it would be if they were absent

On Earth, water in the troposphere is blocked from entering the stratosphereby a cold trap- i.e. cold T° + relatively high ambient pressure minimize theconcentration of water vapor (it condenses out)

On Earth, water in the troposphere is blocked from entering the stratosphereby a cold trap- i.e. cold T° + relatively high ambient pressure minimize theconcentration of water vapor (it condenses out). On Venus the early sea vaporizes, gradually pushing the “cold trap” upwards. The vapor at the top of the atmosphere disassociates, losing its constituent hydrogen.

“THE FAINT YOUNG SUN PROBLEM”

THE EARLY SUN WAS 30%LESS BRIGHT WHEN IT FIRST

STARTED SHINING

SO THE EARTH RECEIVED LESS ENERGY IN IT’S EARLY HISTORY

MAGNITUDE OF GREENHOUSEEFFECT

ONCE OUR SUN BEGAN TO OPERATEAT “FULL CAPACITY”

WHAT ELSE CONTROLED INCOMING ENERGY?

ONCE OUR SUN BEGAN TO OPERATEAT “FULL CAPACITY”

WHAT ELSE CONTROLS INCOMING ENERGY?

Milankovitch cycles

400,000 YEARS