Climate & Weather

1. Climate & Weather Chapters 12, 13, 14

2. What are climate & weather? Climate is the long term variation in weather for a particular area. Weather is the current state of the atmosphere, including short-term variations.

4. How is energy related to climate & weather? The amount of the sun’s energy reaching Earth is equal to the amount of energy radiated back to space in a year. Air and water carry (distribute) energy from one place to another. Climate and weather are a result of the redistribution of Earth’s heat energy.

7. What are air masses? An air mass is a large body of air that takes on the characteristics of the area in which it forms. Cold areas produce cold air masses; warm areas produce warm air masses Air masses over water have higher moisture; air masses over land have lower moisture

9. Air masses change as they move to new areas.

10. How do air masses move? Air masses move as a result of varying densities More dense air masses sink Less dense air masses float Air generally moves from high to low pressure The Coriolis effect deflects this movement Air is deflected to the right in the northern hemisphere (clockwise) Air is deflected to the left in the southern hemisphere (counterclockwise)

12. This results in three basic wind systems Trade winds—occur at 30N and 30S; move west Prevailing westerlies—occur between 30 and 60N and S; move east Polar easterlies—occur between 60N and S and the poles; move west Weird fact: Winds are named according to the direction they come from. (That’s why the names seem backwards.

14. What are fronts? A front is the narrow region separating two air masses with different densities. Fronts can cause dramatic weather changes.

15. Types of fronts Cold front Cold dense air steeply pushes up warm air Produces clouds, rain, & thunderstorms

16. Warm front Warm air gradually pushes cold air away Produces lots of clouds & precipitation

17. Stationary front Two air masses meet and don’t move Temperature & pressure differences are small Little weather is produced

18. Occluded front Warm air is squeezed up by two colliding cold air masses Produces precipitation on both sides

24. What are pressure systems? Moving air creates pressure variations in the atmosphere

25. Sinking air produces high pressure Sinking air pushes air below it out of the way. The Coriolis effect moves this air clockwise Clouds can’t form (at least not very easily)

26. Rising air produces low pressure Rising air is replaced by air nearby The Coriolis effect moves this air counterclockwise Clouds form easily

27. What are the features of the weather? Temperature—the amount of movement of the molecules in the air High temperature & low temperature are measured Measured using a thermometer

28. Precipitation—all forms of water that fall from clouds Forms of precipitation Rain Snow Hail Sleet Precipitation is measured in inches or centimeters

29. Air pressure—the amount of pressure the air puts on our bodies Air pressure decreases as altitude increases Air pressure increases as temperature increases Measured using a barometer, in mm Hg or in Hg

30. Wind Both speed and direction are measured Measured using an anemometer

31. Relative humidity—ratio of water vapor in the air compared to the amount of water vapor the air is capable of holding Measured using a psychrometer, in percent

32. Dew point—the temperature at which dew forms Dew forms because air has cooled to the point of saturation, so condensation occurs

33. What are Earth’s climates? Climates are classified by two factors: Temperature Precipitation There are six main climates Tropical Dry Mild Continental Polar High elevation

36. Climate is correlated with latitude Recall that climate is defined as long term weather patterns