1. Weather
Water in the Air

2. Weather vs. Climate
Weather is the condition of the atmosphere at a certain time and place.
Weather is hard to predict.

3. So what is climate?
Climate is the weather conditions prevailing in an area in general or over a long period.

4. Storms and Air masses
Storms – disturbances with strong winds and precipitation.
Air masses – large volumes of air with distinct properties.

6. Fronts – boundaries between air masses
Warm front
Cold front
Occluded Front
Stationary Front
Storms typically develop at fronts.
Global winds may cause unusual weather by steering air masses.

7. Water Vapor Water Vapor is the amount of moisture in the air.
The warmer the air, the more water vapor it can hold.
The cooler the air, the less water vapor it can hold.

8. Humidity and Relative Humidity
Humidity is the amount of water vapor in the air.
Relative humidity is the amount of water vapor in the air compared with the maximum amount of water vapor that the air has the potential to hold at a certain temperature.

9. Relative Humidity Saturated air has a relative humidity of 100%
The more water vapor in the air, the higher the relative humidity.
Humidity is measured using a psychrometer or hygrometer and a special table.
Paper towel demonstration

10. Humidity
The two factors that affect relative humidity are the amount of water and temperature.
Clouds can form when there are millions of condensed water droplets in the air through the process of condensation.
The water cycle is the natural process that supplies the air with water through evaporation.

11. Dew Point
The dew point is the temperature at which a gas condenses into a liquid.
Condensation cannot occur until the dew point is reached.

13. Rain
A cloud produces precipitation when the water drops in the cloud become large enough to fall.
Rain is the most common form of precipitation.

14. There are four main types of precipitation: rain, snow, sleet, and hail.

15. Sleet forms when rain falls through a layer of freezing air creating falling ice.
Snow forms when temperatures are so cold that water vapor changes directly to a solid.
Snow can fall as a single crystal or join to create snowflakes.
Sleet and Snow

16. Hail
When updrafts of air in the clouds carry raindrops high in the clouds, the raindrops freeze and hail forms.