1. Moisture in the Atmosphere Chapter 11.3

2. Layers of the Atmosphere

3. Heat Transfer

4. Atmospheric Relationships In order to understand the behavior of the atmosphere, one has to understand the relationships between temperature, pressure, and density: When temperature increase so does pressure Heating a closed container can cause it to burst When temperature decreases so does the pressure Car tires on a cold morning have less pressure in them than on a warm day When temperature decrease the density (mass/volume)increases As temperature drops a gas changes in a liquid which is denser (particles are closer together) than a gas When temperature increases the density decreases As temperature increases a liquid changes into a gas which is less dense (particles are further apart) than a liquid

5. How does wind work? Wind is created by the differences in air pressure Cooler air which is more dense sinks and forces warm less dense air up Air generally moves form areas of high density to areas of low density This movement is caused by unequal heating of the Earth’s surface.

6. Moisture in the Atmosphere The amount of water vapor in the air is referred to as humidity Humidity is directly related to temperature The higher the temperature the greater the humidity levels can be meaning as the temperature increases the more water the atmosphere can contain The ratio of water vapor to the volume of air relative to how much water vapor the volume of air can hold is called relative humidity What season do we generally experience the greatest humidity levels? Summer – because the temperatures are higher as is the capacity of the air to hold more water which increases the amount of humidity

7. Cloud Formation Clouds form when warm air is forced up in a convection current As the air rises, the temperature decrease causing the water vapor to condense around a condensation nuclei (small particles) Clouds can also form when wind encounters a mountain is forced upward This is referred to as orographic lifting

8. Process of Cloud Formation As the ground is heated, warm moist air rises As the warm air rises heat will be lost at a rate of 10°C per 1000 m Dry adiabatic lapse rate As the cooling air continues to rise it will reach the lifted condensation level (height at which condensation of the water vapor in the air occurs or the height at which the cloud will start to form) The lifted condensation level will vary depending on the dew point. The dew point is the temperature to which air must be cooled at a constant pressure to reach saturation The saturated air will continue to rise and lose heat on average at a rate of 4°C – 9°C per 1000 m per 1000 m Moist adiatic lapse rate

9. Adiabatic Lapse Rates and Cloud Formation

10. Types of Clouds Clouds are classified by shape and height Shape and height vary because of temperature, pressure, and amount of water vapor Four main types (based on shape)- Cirrus, Stratus, Cumulus, and Nimbus Three main heights- Cirro (high), Alto (middle), Strato (low)

11. Types of Clouds

12. What happens when the air can no longer hold the water!!!! When the air can no longer hold the water, the water falls from the sky as precipitation Precipitation is determined by air temperature Rain- in warm air, water vapor forms rain Snow- cold air causes water vapor to form snowflakes Sleet- small ice pellets Hail- lumps of ice