Earth’s Atmosphere and Weather

The earth has layers on the inside and layers on the outside, aka the atmosphere. From the outside in: Thermosphere - Mesosphere - Ionosphere - Hot outer layer, hit by a lot of solar radiation. Temps at ~ 980 o C or 1,796 o F The lower Thermosphere and upper Mesosphere, filled with ions that bounce radio waves long distances across earth. This layer doesn’t absorb much radiation, so the temp drops to below -80 o C or -112 o F

The troposphere refers to every part of the atmosphere that is below the strato- sphere all the way to the ground. Most weather takes place in this layer. The top layer of the Stratosphere has a lot of ozone molecules which absorb and react with that got through. the upper layers. Stratosphere - Troposphere - Ozone Layer - The bottom of the strato- sphere is very cold at, but the top is warmer at from the reactions in the Ozone Layer. UV radiation ~ -55 o C or -67 o F ~0 o C

The earth’s atmosphere is mostly made up of: Nitrogen (78%), Oxygen, & Carbon (CO 2 ) The oxygen comes from photosynthesis of plants, algae, and bacteria. The nitrogen and carbon can come as wastes from living things as they consume nutrients. The nitrogen and carbon can also come from. reactions such as burning gasoline or can come from erupting volcanoes. combustion O2O2 O2O2

The Water Cycle Water turns into steam by evaporation and transpiration ground back to the oceans, lakes and plants. It then condenses in the lower atmosphere & eventually precipitates as rain, snow, etc. The water then flows over the ground as rivers and under the (oceans and lakes) (evaporation directly from plant leaves).

When air warms up, more water evaporates or transpires. This makes warm, humid air and when you warm a fluid, the warm, humid air will expand, become less dense and rise. As the air rises, it cools and then it will become more dense and it will eventually sink.

Warm, expanded, low density, rising, humid air pushes down on the bottom of the atmosphere with low-pressure. Cooling, high density, sinking, dry air pushes down on the bottom of the atmosphere with high-pressure.

High pressure systems push hard and low- pressure systems push weakly, so air moves from high to low. Whenever warm air rises, it has to eventually fall. Most of the rising warm on the Earth occurs at the equator. After moving away from the equator and rising to the cold upper atmosphere, the air cools and sinks back down.

So, there is a continuous flow of air moving in the upper troposphere from the southwest to the northeast and air moving in the lower troposphere from the northeast to the southwest. This push of air is usually called cold warm wind. Sometimes, this movement comes in spurts where a large mass of warm or cold air will suddenly move into an area.

If a large mass of warm, humid air suddenly runs into a pocket of cold air, then the warm air will the cold air and the water vapor in it will cool and to make clouds and slow, steady precipitation that will usually last a few days. rise above condense

If a large mass of cold, dry air suddenly runs into a pocket of moist, warm air, then the cold air will the warm air, forcing it to rise very quickly. As the warm, humid air rises and cools quickly, a great deal of wind is made, big clouds form very quickly and a lot of rain comes down, frequently as big storms. This is a COLD front. plow under

The big masses of moving warm air are called. and they generally make steady rain or snow as they pass through. The big masses of moving cold air are called. and they generally make big cumulonimbus clouds and storms. warm fronts cold fronts

Occluded Front When a warm air mass is caught between two cooler air masses. The warm air rises, is trapped, cools, and forms cloudy skies and rain.

As very warm air rises off of warm, tropical oceans, it can cause a chain reaction of rising, moist air leading to condensation and eventually a huge amount of circulating cold air, plummeting back to the ground very fast as a hurricane (>119km/h). When storms occur and warm air rises rapidly, it can start circulating in the clouds due to the Earth’s rotation. When a vertical cylinder of rotating air develops, it can sometimes sink down to touch the ground as a tornado.

Stationary Front - When two unlike air masses form a boundary, but neither is moving. Cyclone - a weather system with a center of low pressure. Anticyclone - has a center of high pressure and clockwise winds in the Northern Hemisphere. Generally clear weather is seen with this. Weather map symbols: 1. cold front; 2. warm front; 3. stationary front; 4. occluded front; 5. surface trough; 6. squall/shear line; 7. dry line; 8. tropical wave

Isotherms - lines on a weather map connecting points with the same temperature. Climate - a description of the pattern of weather over a long time in a region. Temperature and precipitation are the two main factors that determine a region’s climate.

Earth’s Motion Rotation - Spinning of the Earth on its axis. One Rotation = 1 day Revolution - The time it takes the Earth to go around the sun once is days. Also known as an orbit. One orbit for the Earth takes one year.

Latitude Zones Polar Temperate Equator Temperate Polar Notice how the run’s rays are spread out toward the poles but hit more directly at the equator. How would this affect weather? Colder toward the poles & warmer at the equator.

Heating the Earth If 30% of the energy reaching earth is reflected back into space and about 20% is absorbed by the atmosphere, how much will be absorbed by the surface of the Earth? The Earth’s atmosphere is heated mainly by energy reradiated by Earth’s surface.

Winds are caused by differences in air pressure. Local winds occur where land meets a large body of water. Global winds blow over long distances from a specific direction Trade winds, westerlies, & polar easterlies are global winds. See page 758 in your book. The Jet Stream is a belt of high-speed winds in the upper troposphere.

Clouds - a dense, visible mass of tiny water droplets and ice crystals. The main forms are: stratus, cumulus, and cirrus..

Flat layered clouds are stratus (spread out) –Nimbostratus produce precipitation Cumulus are puffy fair weather clouds –Thunderheads or cumulonimbus produce thunder, lightning, and precipitation Cirrus are thin, wispy clouds found at high altitudes –These generally produce no rain

nimbostratus cumulus cumulonimbus cirrus

Precipitation The amount of water in the air is called humidity. The amount of humidity present is dependent upon temperature At high temps, the air holds more moisture as vapor. At low temps, this vapor condenses and forms dew, clouds, frost (if cold enough) or fog. Both rain and freezing rain can fall as liquid. Hail is solid pieces of ice >5 mm in diam.

Continental polar air masses form over land north of 50 o north latitude. Several factors that can affect a region’s temperature are: 1.Ocean currents 2.Latitude and altitude 3.Distance from large bodies of water A aa A Maritime tropical air mass will form over a large body of water affecting weather of land nearby.

Etc. As altitude increases, temperature falls 6.5 o C per kilometer. If the temperature at 1000 m is 20 o C, what would the temperature be at 3000 m? The change in altitude is 2000 m or 2 km. 2km x 6.5 o C = 13 o C fall km So: = 7 o C at 3000 m

Another Etc. Oxygen makes up about 20.9 % of the volume of dry air. About how much oxygen would there be in a 3000 m 3 volume of dry air? 3000 m 3 x = 627 m 3