Weather - Atmosphere

What causes weather? Water in the atmosphere causes the weather we have on Earth

Make-up of the atmosphere The atmosphere is made up of a mixture of gases – Most abundant element in the atmosphere – Nitrogen 78% 2nd most abundant element – Oxygen 21% The remaining 1% is made up of a mixture of gases – argon, carbon dioxide, water vapor

Does the atmosphere have mass? The atmosphere extends 700 km high and is filled with gas molecules – does it have mass?

At Sea level – every square inch weighs about 15 pounds At Sea level – every square inch weighs about 15 pounds! The air molecules are pulled toward Earth by Gravity – which keeps the atmospheric gases from floating away. The amount that the atmosphere is pushing on the surface of the earth is called Air Pressure

Air Pressure Air Pressure is affected by Altitude & Atmospheric composition Most of the air pressure is located close to the surface of the earth because this is where most of the atmospheric gases are found.

Layers of the atmosphere Troposphere The lowest layer of the atmosphere Densest layer – contains almost 90% of the atmosphere’s total mass Almost all gases and living things are found in the troposphere

Stratosphere Layer above the troposphere Gases do not mix as much as in troposphere Air is very thin, contains little moisture Lower stratosphere temp averages -60 C Temperature rises with altitude, due to the ozone layer

Mesosphere Middle Layer Coldest Layer Temp decreases as altitude increases Temp reach -93C at the top of mesosphere

Thermosphere Uppermost layer Temp increases with altitude Atoms absorb solar radiation and release thermal energy – causes temp to be 1000C or higher Doesn’t feel hot – because air molecules are so spread out that the molecules rarely touch

Ionosphere Located in the upper Mesosphere and lower thermosphere Contains electrically charged particles (ions) that absorbed harmful solar energy The ions radiate energy as shimmering lights called auroras

Questions What is the most abundant gas found in the atmosphere? What produces this gas? What 2 things affect air pressure? Which layer of the atmosphere do we live in? What causes the weather on Earth? Which layer of the atmosphere contains the Ozone Layer – what does the ozone layer do for us?