1. State of the Atmosphere

2. What’s it like?
Sunny, cloudy, rainy, cold.. These are all words that describe the state of the atmosphere
Scientists use words like temperature, air pressure, wind speed, and the amount of moisture in the air

3. Temperature vs. Heat
First, most of us think of temperature and heat as the same thing.. But they’re not!
Temperature: measure of how rapidly or slowly molecules move around
Faster moving molecules = higher temp LINK
Heat: the transfer of energy that occurs because of a difference in temperature between substances
Heat flows from areas of high temperature to areas of low temperature LINK
So, heat is the transfer of energy, and temperature is how we measure and interpret that energy!

4. Measuring Temp Review:
Temperature can be measured in Fahrenheit, Celsius, or in Kelvin
Celsius is easiest because 100 is boiling water, and zero is freezing of water
Temperature is measured with a thermometer

5. To convert from Celsius to Farenheit, multiply by 9, divide by 5 and add 32!
Try 37C into Farenheit….

6. Dew Point
The temperature to which air must be cooled at a constant pressure to reach saturation.

7. - This is when dew forms!
When this temperature falls below freezing, frost will form!

8. Condensation
Until the air is saturated, or until the dew point is reached, condensation cannot occur
Condensation is when gas changes to a liquid.

9. In this case, water vapor changes to liquid water and falls as rain or lands on surfaces as dew
Condensation is also what happens when water droplets form on the outside of cups/cans

10. Vertical Temperature Changes
The temperature on a mountain is lower than at lower elevations.
Temperatures decrease as it gets farther away from the heat source = temperature inversion.

11. Air masses also cool as they rise, and when they cool enough, it will reach the dew point
The height at which condensation occurs is called the lifting condensation level.
After this height, air cools more slowly.

12. Air Pressure Air pressure: the weight of the air above our heads
As you go down into the oceans, the pressure gets heavier, because there is more matter above you
Oppositely, as you go up in the atmosphere, there are fewer and fewer molecules exerting pressure, therefore, the air pressure is less

13. Wind
Cool air, being more dense, sinks and forces warm, less dense air, upwards
Air moves because of a density imbalance = wind
These imbalances create high and low pressure areas

14. Wind is the movement of air from a high pressure area to a low pressure area
Wind is measured in miles per hour, or km per hour
Wind is measured with an anemometer

16. Relative Humidity Humidity is the amount of water vapor in the air
The amount of water vapor in the air compared to how much water vapor the air could hold is called relative humidity.
What time of year do we experience the most humidity??

17. Warm air can hold more moisture than cold
Expressed as a percentage - if an amount of air is holding as much water vapor as it can, its relative humidity is 100%

19. Measuring Relative Humidity
Relative humidity is measured with a hygrometer/pyschrometer

20. High and Low Pressure Areas
H’s and L’s on a weather map
High pressure = air is being forced down = sunny skies 
Low pressure = air is being forced up = usually rainy/thunderstorms 
Air pressure is measured on a barometer L

21. Moisture in the Atmosphere
Chapter 11.3

22. Cloud Formation
Clouds form when warm, moist air rises, then expands and cools in a convection current

24. As the air reaches it’s dew point, the water vapor in the air condenses around condensation nuclei.
Condensation nuclei: small particles in the air where cloud droplets form
When millions of these nuclei collect together, a cloud forms

25. 2 Ways Clouds Form
1. Orographic Lifting: Cloud formation that occurs when warm moist air is forced to rise up the side of a mountain.

26. 2. Collision of Air Masses: when in contact with cooler air, warm air tends to rise above the cooler air. Then, the warm air cools and as this happens the water vapor in it forms a cloud

27. Cloud Classification High Clouds – form above 6000m Mostly Ice Cirro
Types of Clouds
Clouds Made Of…
Height Words
Shape Words
High Clouds – form above 6000m
Mostly Ice
Cirro
Cirrus: wispy, stringy, hair-like, feathery
Middle Clouds- form at m
A Mixture of Ice and Liquid
Alto
Cumulus: puffy, lumpy looking
Low Clouds- form at 2000m
Liquid
Strato
Stratus: smooth, sheets of clouds
Example: A cirrocumulus cloud is a high, puffy, lumpy looking cloud
Nimbus/Nimbo: gray, rain clouds

28. Cloud Types

29. Precipitation
Clouds are made of water droplets that join together in a process called coalescence
If the process continues, the droplet becomes too heavy to stay in the cloud and it falls to Earth as precipitation
Precipiation includes both liquid and solid form
The main types are rain, snow, hail, and sleet

31. What Type of Precipitation Will Form?
High Clouds – Ice Crystals
Lower Clouds – Water Droplets
Warm Air = Rain
Cold Air = Freezing Rain, Sleet, or Snow

32. Types of Precipitation
Rain = Water Droplets
Sleet = Water Droplets that FREEZE into solid pellets in the air
Freezing Rain = Water droplets that FREEZE when they hit frozen surfaces
Snow = Ice crystals that stay frozen
Hail = layered frozen balls of ice

33. Sleet
Freezing Rain
Hail

34. How in the Hail?
Cumulonimbus Clouds
Hail Video

35. The Water Cycle The amount of water on Earth stays constant
Water moves from atmosphere to ground constantly
The constant movement of water between the atmosphere and Earth’s surface is called the water cycle.

36. Energy is received from the sun
This energy causes liquid to change into gas and rise into the air
This is called evaporation (liquid to gas). Gas form of water is water vapor.
As water vapor rises, it cools and changes back into a liquid
This is called condensation (gas to liquid)
When water vapor condenses it forms clouds
In the clouds, the water droplets collide and form precipitation
Then, water that has fallen is soaked back into the ground, or enters bodies of water
Then the cycle starts all over again