The air mass behind a warm front is likely to be warmer and more moist than the one before the front. If a warm front is approaching, light rain or light winter precipitation is possible before and as the front passes. Behind the front, expect clearing skies, warmer temperatures and higher relative humidities.
The answer is b an astronomical unit
With the recent technologies and scientific innovations we have now on studying and providing detailed analyses of the polar ice cores, it is roughly estimated that we could profile the ancient climate the Earth had in a time period as early as 800,000 years in order to explain the most recent climate change.
The answer is:
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The hydrosphere.