1. Notes on Weather A.Weather is the short term condition of the atmosphere over a small area. B.Weather is described by its conditions, or variables that change every day. 1. temperature - indicates the amount of heat in the atmosphere and is measured with a thermometer 2. Air pressure- air has mass; it is the force that presses down on earth a. Caused mainly by changes in temperature and altitude. b. The force is measured with a barometer in either inches of mercury or millibars Pg. 127

2. 3. Humidity - the amount of water vapor in the air a. Warm air absorbs more water vapor than cool air; so air temperature determines how much water vapor can be absorbed b. Relative humidity - a comparison of the actual amount of water vapor in the air with the maximum amount the air could absorb at that temperature 1. psychrometer - instrument used to measure relative humidity; a wet and dry bulb thermometer is one type

3. 4. Wind - the horizontal movement of air over the Earth’s surface a. Wind speed - a measure of how fast the air is moving, in miles or kilometers per hour 1. anemometer - instrument used to measure wind speed b. Wind direction - the direction from which the wind is coming 1. weather vane or wind sock - instrument used to determine wind direction

4. 5. Precipitation - water, in any form that falls from the atmosphere a. Temperature determines the type of precipitation produced b. Types: 1. Rain - most common 2. Sleet - rain that falls through a layer of air below freezing; smaller than 5mm 3. Hail - ice larger than 5mm; updrafts push small ice pellets to higher parts of the cloud where a new layer of ice may form; when too heavy it falls 4. Snow - water vapor in a cloud that form ice crystals c. Rain Gauge - instrument used to measure the amount of precipitation in inches

5. Notes on Clouds A.Clouds 1. Clouds are millions of tiny droplets of water or ice crystals 2.Clouds form: a. When condensation occurs b. Temperature at which condensation occurs is the dew point. c. Water vapor condenses around small particles such as dust (soil) salt, smoke d. Water vapor that condenses on grass or on your car is called dew.

6. 3. Cloud Types- clouds are described by height and shape a. Height 1. Cirro – high clouds 2. Alto – middle clouds 3. Strato – low clouds b. Shape 1. Cirrus – have a feathery look 2. Cumulus – means “heap” or “mass” 3. Stratus – means spread out c. Fog – clouds that form near the ground d. Nimbus – means rain

8. CLOUDS

9. Notes on Weather A.___________ is the short term condition of the atmosphere over a small area. B.Weather is described by its conditions, or variables that change every day. 1. ______________ - indicates the amount of heat in the atmosphere and is measured with a ______________ 2. _____________ - air has mass; it is the force that presses down on earth a. Caused mainly by changes in temperature and altitude. b. The force is measured with a ________________ in either inches of _____________ or ________________

10. 4. _________________ - the horizontal movement of air over the Earth’s surface a. _______________ - a measure of how fast the air is moving, in miles or kilometers per hour 1. ________________ - instrument used to measure wind speed b. ______________ - the direction from which the wind is coming 1. _______________ - instrument used to determine wind direction

11. 3. ________________ - the amount of water vapor in the air a. Warm air absorbs more water vapor than cool air; so air temperature determines how much water vapor can be absorbed b. ________________- a comparison of the actual amount of water vapor in the air with the maximum amount the air could absorb at that temperature 1. ________________ - instrument used to measure relative humidity; a wet and dry bulb thermometer is one type

12. 5. ________________ - water, in any form that falls from the atmosphere a. Temperature determines the type of precipitation produced b. Types: 1. ___________ - most common 2. ___________ - rain that falls through a layer of air below freezing; smaller than 5mm 3. ___________ - ice larger than 5mm; updrafts push small ice pellets to higher parts of the cloud where a new layer of ice may form; when too heavy it falls 4. ___________ - water vapor in a cloud that form ice crystals c. ________________ - instrument used to measure the amount of precipitation in inches