1. Elements of Weather 1

2. Unit 4 Lesson 2 Elements of Weather
Florida Benchmarks
SC.6.E.7.2 Investigate and apply how the cycling of water between the atmosphere and hydrosphere has an effect on weather patterns and climate.
SC.6.E.7.3 Describe how global patterns such as the jet stream and ocean currents influence local weather in measureable terms such as temperature, air pressure, wind direction and speed, and humidity and precipitation.
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3. Wonder About Weather? What is weather? Elements of Weather
Weather is the condition of Earth’s atmosphere at a certain time and place.
Short-term state of the atmosphere
Weather conditions in the atmosphere can be recognized through direct
observation.
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4. Elements of Weather What is temperature and how is it measured?
Temperature is how hot or cold something is.
Thermometers are used to measure temperature.
Some thermometers use the thermal expansion of a liquid to determine temperature.
Electrical thermometers use the strength of an electric current to determine temperature. 4

5. What is humidity and how is it measured?
Elements of Weather
What is humidity and how is it measured?
Humidity is the amount of water vapor in the air.
As more water evaporates, humidity increases.
Relative humidity is the amount of water vapor in the air compared to the amount of water vapor needed to reach saturation.
Air is saturated when
The rates of
evaporation and
condensation are
equal. 5

6. What is humidity and how is it measured?
Elements of Weather
What is humidity and how is it measured?
Dew point is the temperature at which more condensation than evaporation occurs.
When air temperature drops below the dew point, condensation forms dew, fog, and clouds. 6

7. What is precipitation and how is it measured?
Elements of Weather
What is precipitation and how is it measured?
Precipitation is any form of water that falls to Earth’s surface from the clouds, including rain, snow, hail, and sleet.
Rain forms as water condenses. 7

8. What is precipitation and how is it measured?
Elements of Weather
What is precipitation and how is it measured?
Snow forms when temperatures are low enough to turn water vapor into a solid.
Hailstones are layered
lumps of ice formed
during severe
thunderstorms. 8

9. Watching Clouds Elements of Weather
Cirrus clouds are made of ice and appear feathery or wispy.
Cumulus clouds appear as heaps or piles. They form in fair weather
but can
produce
thunderstorms.
Stratus clouds
form flat layers
that can block
out the sun and
produce steady
rain. 9

10. The Air Out There What is air pressure and how is it measured?
Elements of Weather
The Air Out There
What is air pressure and how is it measured?
Air pressure is the force of air molecules pushing on an area.
- Result of the weight of a column of air pushing
down on an area
- Changes in the atmospheric
pressure as shown by a
barometer.
A barometer is used to measure
air pressure.
Air pressure and density
decrease with altitude. 10

11. What is wind and how is it measured?
Elements of Weather
What is wind and how is it measured?
Wind is air that moves horizontally, or parallel to the ground.
Over a short distance, air moves from higher pressure to lower pressure.
An anemometer is used to measure wind speed.
A wind vane or wind sock is used to measure wind direction. 11

12. What is visibility and how is it measured?
Elements of Weather
What is visibility and how is it measured?
Visibility is a measure of the distance at which an object or light can be clearly seen.
Visibility is measured by using three to four known landmarks at different distances.
Air pollution or fog can cause poor visibility.
FYI
Observer:
Eye level at h = 5 ft 7 in (1.70 m)
Horizon = 2.9 miles (4.7 km)
Standing on a hill or tower
100 feet (30 m) in height,
Horizon = 12.2 miles (19.6 km) 12

13. What are some ways to collect weather data?
Elements of Weather
What are some ways to collect weather data?
Weather data can be collected at ground stations, by weather buoys, by ships, by airplanes, and by satellites. 13