11.2- State of the Atmosphere 11.3- Moisture in the Atmosphere 11.1- Atmospheric Basics 11.2- State of the Atmosphere 11.3- Moisture in the Atmosphere

Atmospheric Basics Atmospheric Composition The majority of air is made up of oxygen(21%) and nitrogen(78%).

Atmospheric Basics Key Atmospheric Gases Carbon dioxide and water vapor are two important gases that vary in amount but are critical in determine the amount of energy the atmosphere absorbs. Heat is either absorbed or released when water changes state. Three states in the atmosphere are liquid, solid, and gas.

Atmospheric Basics Ozone A gas that controls the amount of ultraviolet light that enters the atmosphere is ozone, a molecule made up of three oxygen atoms. Other major gases that can be found in the atmosphere include neon, helium, methane, krypton, hydrogen, and xenon.

Structure of the Atmosphere

Atmospheric Basics Layer Temperature Variation and Altitude Composition Special Characteristics Troposphere Decreases with altitude Most of mass of atmosphere, water vapor Most weather occurs here, pollution accumulates Stratosphere Increases with altitude Concentrated ozone Ozone layer Mesosphere No concentrated ozone Upper boundary is the menopause Thermosphere Little atmospheric gases, molecules spread far apart Ionosphere

Atmospheric Basics The exosphere is the outermost layer of the Earth’s atmosphere. Helium and hydrogen are found here.

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Atmospheric Basics Solar Fundamentals Radiation is when energy is transferred by visible light, ultraviolet radiation, and other electromagnetic waves. Conduction occurs when molecules collide. Convection is the transfer of energy by the flow a heated substance. Convection currents are the main mechanisms for the vertical motion of air that cause different weather patterns. Winds form from convection currents.  

Atmospheric Basics Reflection of the Sun’s energy. Effect Percent Reflected by the atmosphere 6% Absorbed by Earth surface 50% Reflected from cloud 25% Reflected from Earth surface 4% Absorbed by atmosphere 15%

State of the Atmosphere Temperature vs. Heat Temperature is the measurement of how quickly or slowly molecules move. Heat is the transfer of energy. Heat flows from areas of higher temperature to areas of lower temperatures.

State of the Atmosphere Temperature is measured the following ways. Degrees Fahrenheit = oF Degrees Celsius = 0C Kelvin = K There is no colder temperature known than absolute zero on the Kelvin scale.

Temperature Scales

State of the Atmosphere Dew Point The dew point to which air must be cooled at constant pressure to reach saturation, point at which air holds all the water vapor it possibly can. Condensation occurs when matter changes from a gas to a liquid.

State of the Atmosphere Vertical Temperature Changes Temperature decreases as you go up Lifted condensation level LCL: Height where condensation occurs Air rises, cools, condenses Clouds: water vapor condensing

State of the Atmosphere Air Pressure and Density Air pressure Weight of atmosphere above you decreases as you go up Density Air is more dense at surface of Earth and decreases as you go up

Air Pressure

State of the Atmosphere Pressure –Temperature-Density Relationships Temperature inversion is an increase in temperature with height in an atmospheric layer. (Temperature- altitude relationship is inverted.) Step 1: Cool, clear winter night when the wind is calm Step 2: Lower layers of atmosphere lose heat Step 3: Lower layers of atmosphere become cooler than layers above. Step 4: Temperatures increase with altitude, creating the temperature inversion.

Pressure-Temperature Graph

State of the Atmosphere Wind Cool air sinks, creating an area of high pressure. Warm air rises, creating an area of low pressure Air masses move from areas of high pressure to low pressure, which creates wind. Measured in miles per hour Wind is more varied on surface of Earth due to friction with water, land, trees, etc….

State of the Atmosphere Relative Humidity Humidity is the amount of water vapor in air. Warm air can hold more water vapor. Climates near the equator are more humid than climates close to the poles. Relative humidity is the ratio of water vapor in a volume of air relative to how much water vapor that volume of air is capable of holding. Given in %. Ex: 50% holding half the water it can

Moisture in the Atmosphere Cloud Formation Clouds can form as warm moist air rises, expands, and cools and cooler air sinks in a convection current. Water vapor in the air condenses on a condensation nuclei such as dust or ice. As more and more droplets collect, a cloud is formed. Clouds also form from orographic lifting where moist air comes in contact with a mountain and rises. Another type of cloud forms when air masses of different temperatures collide.

Cloud Formation

Moisture in the Atmosphere Stability is the ability of an air mass to resist rising. Air becomes unstable if it is cooler than the surface beneath it. If temperature conditions are right and the air masses rise rapidly, it can produce clouds associated with thunderstorms. Latent Heat is stored energy.

Moisture in the Atmosphere Types of Clouds Altitude Strato: Low: below 2000m Alto: Middle: 2000 – 6000m Cirro: High: above 6000m (ice crystals) Shape Cirrus: wispy, stringy Cumulus: puffy, lumpy Stratus: featureless sheets Nimbus: low, gray (rain) Draw an example of each based off the slide.

Types of Clouds- Draw in notes

Moisture in the Atmosphere Precipitation Coalescence is the process that forms large droplets due to the collision of two cloud droplets. Precipitation includes all forms of water both liquid and solid that fall from the clouds. Forms of Precipitation are: rain, snow, sleet, and hail

Moisture in the Atmosphere The Water Cycle Precipitation- rain, ice, snow, etc… Transpiration- water loss from plants Evaporation- water to water vapor (gas). lakes/oceans into air Condensation- water vapor to water. Dust; clouds Runoff- water running into bodies of water

Water Cycle