The Atmosphere

The Atmosphere Earth’s atmosphere serves a vital role in our survival, it Blocks harmful uv rays Maintains our warm temperature Supplies the oxygen we need to breathe As we learned in out last unit, our activities have comprised the atmosphere’s role in protecting us

The Atmosphere Earth’s atmosphere is comprised of 78% Nitrogen, 21% Oxygen, and 1% of other gases that surround the planet. Water vapor makes up part of the “other” 1%, but can fluctuate between 0 and 4%. The higher the water vapor, the more Nitrogen and Oxygen decrease.

Atmospheric Concentrations

The Atmosphere The further we go out from Earth’s surface, the thinner the atmosphere is, until it reaches space The atmosphere is broken into four main layers (we’ve reviewed the first 2 already) followed by the exosphere – which is basically outer space Troposphere Stratosphere Mesosphere Thermosphere ( contains the ionosphere)

The Atmosphere Troposphere First layer above Earth’s surface (reaches from 7-20km above the ground) Half of Earth’s atmosphere exists in the troposphere Weather occurs in the troposphere We also previously learned that pollution in this layer causes smog and bad ozone production

The Atmosphere Troposphere (cont) This layer is heated from the ground (as the sun warms the Earth, the ground radiates, or heats) the troposphere. So, the further upward we go into the troposphere, the colder it gets. The air also gets thinner the higher up you go (this is what it get’s harder for some people to breathe in higher elevations, such as mountains Most the water vapor and dust particles in the exist in this layer, so most clouds occur here.

Kinds of Clouds 3 basic kinds… Cirrus – light and feathery. Made of ice crystals at 10,000m Cumulus – big and puffy. Made from rising currents of warm air that build to great heights Stratus – sheet like. Form layer upon layer at low altitudes.

Fog A cloud that forms near the ground is fog. Fog forms from condensation. You see this when cool air moves in over warm air usually in… Valleys Rivers Lakes Other low areas

Cumulonimbus Clouds Cumulus clouds that are associated with thunderstorms. Updrafts can raise high to the top of the troposphere. The top flattened and looks like an anvil. An anvil is a good indication a thunderstorm is coming.

Let’s Name that Cloud….

Let’s Name that Cloud….

Let’s Name that Cloud….

Let’s Name that Cloud….

Let’s Name that Cloud….

The Atmosphere Stratosphere 2nd layer from Earth’s surface (between 16-50 km above the Earth) Very stable, allowing for jet aircraft to fly here to avoid the turbulence they experience in the troposphere The ozone layer exists here, absorbing radiation from the sun. This process heats the stratosphere. The further up you go into the stratosphere, the hotter it gets (opposite of the troposphere) Very little water vapor here, so almost no clouds (polar stratospheric clouds are the exception - PSCs)

PCSs Found at altitudes of 15 to 25 km (9.3 to 15.5 miles They appear to help create “Ozone Holes” by encouraging certain chemical reactions that destroy ozone.

PCSs

The Atmosphere Mesosphere Third layer up from the Earth. Goes from 50-85km high The higher you go up in the Mesosphere, the colder it gets (like the troposphere) We don’t know much about this layer, because satellites orbit above it, and weather balloons and jet aircraft can’t fly high enough to reach it We know that most meteors from space burn up in this layer (so we don’t get hit by them often) One kind of cloud forms here – Noctilucent Clouds

Noctilucent Clouds A special type of clouds, called "noctilucent clouds“ (PMCs), sometimes forms in the mesosphere near the North and South Poles. They form much higher than any other type of cloud There are also odd types of lightning in the mesosphere. These types of lightning, called "sprites" and "ELVES"

PMCs

The Atmosphere Thermosphere 4th layer from the Earth (goes from 90km – between 500-1000km high) Temperatures sharply increase the higher you go in the thermosphere and is influenced by solar activity (from 200-2000 degrees C or 360-3632 degrees F) Even though it’s considered part of Earth’s atmosphere, the air density is so low that it’s considered mostly the same as outerspace. Aurora (the Southern and Northern Lights) occur here

Atmospheric Temperatures

The Atmosphere Thermosphere The lower portion of the thermosphere is called the Ionosphere The ionosphere is a layer of electronically charged particles When solar energy collides with these particles, it creates ions and free electrons, which interfere with radio waves sent from Earth, bouncing them back. This is how AM radio transmissions can bounce from one side of the Earth to the other.

Radio waves and the Ionosphere

The Atmosphere Exosphere Above the Thermosphere, where outer space starts. For most part, not considered Earth’s atmosphere The is the layer where air molecules escape into space Space shuttles orbit the Earth here There are so few to no air molecules, so there is no wind. So the wings of the shuttles(which are used in the lower layers) are useless here