1. Weather Conditions

2. What Makes up Earth’s Atmosphere?
The layer of air surrounds our planet is called the atmosphere.

3. Layers of the Atmosphere
Troposphere
Stratosphere
Mesosphere
Thermosphere

4. Troposphere Layer closes to the earth Weather happens in this layer
Live and breathe air in this layer
Air temperature decreases as you go higher

5. Stratosphere Airplanes travel in this layer to avoid bad weather
Contains most of the atmosphere’s ozone
Ozone protects living things from harmful rays of the sun
Temperature increase with height

6. Mesosphere Temperature decrease with height
Coldest layer of the atmosphere

7. Thermosphere Hot, outermost layer
Temperature increase quickly with height

8. How Do Air Masses Affect the Weather

9. Greenhouse Effect

10. Air Masses

11. What happens when to air masses meet?
When two air masses meet, they form a border called a front
A front is the area where two air masses meet and weather happens

12. Cold Front A cold air mass catches up with a warm air mass
The cold air mass forces the warm air up in the atmosphere
As warm air

13. Cold Front As warm air pushes upward, it cool and forms cloud.
Rain develops.
Thunderstorm often occur along a cold front.

14. Cold Front Generally move from northwest to southeast
Air behind a cold front is colder and drier than the air ahead of it.
When a cold front passes through, temperatures can drop more than 15 degrees within the first hour.
Represented by a solid lines with triangles along the front pointing towards the warmer air and in the direction of movement

16. Warm Front Forms when a warm air mass catches up with a cold air mass
Warm air slides up over the colder, denser air

17. Generally move from southwest to northeast
Air behind a warm front is warmer and more moist than the air ahead of it

18. Represented by a solid line with semicircles pointing towards the colder air and in the direction of the movement
Steady rain or snow may fall as the front approaches and passes

19. Common Characteristics of Warm Fronts
Before Passing
While Passing
After Passing
Winds
South-southeast
Temperatures
Pressure
Clouds
Precipitation
Visibility
Dew Point

21. Clouds and Weather
Weather scientists classify a cloud based on its shape, its color, and where it forms in the atmosphere

22. Cirrus
A wispy white cloud
Fair weather

23. Cumulus Puffy cotton-ball clouds
Begins to form when water droplets condense at middle altitudes

24. Cumulonimbus Dense cumulus cloud with a hazy outline
Usually producing heavy rain, thunderstorms, or hailstorms

25. Stratus Dark gray clouds that form a low layer
Sometimes bring rain or snow showers

26. What is a Cycle?
A sequence of events that repeat themselves

27. Evaporation The sun heats up water in rivers, lakes, or ocean
The water changes from a liquid into a gas, vapor, or steam.
The water vapor leaves the rivers, oceans, or lakes and goes into the atmosphere.

28. Condensation
Water vapor in the air gets cold and changes back into liquid
forming clouds

29. Transpiration
Is the process by which plants return water to the atmosphere.
After absorbing water from the ground, plant release water through their leaves.
This helps plants stay cool.

30. Precipitation
Occurs when so much water has condensed that the air cannot hold it anymore.
Clouds get heavy and water falls back to earth in the form of rain, sleet, hail, or snow

31. What instruments do meteorologist use to forecast weather?

32. Anemometer Measures wind speed
The cups catch the wind, turning a dial attached to the instrument.
The dial shows the wind speed.

33. Barometer
Measures air pressure

34. Psychrometer
Measures relative humidity, using the cooling effect of evaporation

35. Hygrometer
Measures the amount of humidity in the air.