Earth Science Chapter 18 Review
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14 terms
Terms | Definitions |
|---|---|
 What is unique about water? | Water exists commonly in our environment as a solid, liquid or gas. |
| What is specific humidity? | Specific humidity is the actual amount of water vapor in the air at a given time and place. It is measured in grams of water per kilogram of air. |
| Describe what it means when the air is saturated? | Saturated air means that the rate of condensation equals the rate of evaporation, and that the air cannot hold any more water. |
| What is relative humidity? | Relative humidity is how close the air is to holding its maximum capacity for water vapor. It is expressed in a percent. |
| Describe two ways of measuring humidity? | One way of measuring humidity is by using a sling psychrometer. There is a wet-bulb thermometer on the end of the sling, and you swing it around until the water evaporates. Then you calculate the difference between the the wet bulb thermometer and the dry bulb thermometer, and with this data, you can calculate the specific humidity. (This is the only way of calculating humidity that we need to know for the midterm.) |
| What happens when air has reached its dew point and why does it happen? | When the air reaches its dew point, the air cannot hold any more water, so water condenses. When it condenses on the grass, it forms dew. When it condenses in the air, it forms clouds and/or fog. |
| What must be present in order for a cloud to form? | Condensation nuclei must be present in order for a cloud to form. |
| Name the there main types of clouds. What prefix indicates a high level cloud? What prefix indicates a middle level cloud? | The three main types of clouds are cirrus, stratus, and cumulus. The prefix alto-means a middle level cloud. The prefix cirro- means a high level cloud. |
| What do we call a cloud that is found at Earth's surface? Which of the three main types is it? | A cloud found at Earth's surface is called fog. Fog is actually a type of stratus cloud. |
| What does the term condensation level refer to? | The atmospheric level at which condensation occurs. |
| What is a cumulonimbus cloud? Is the air inside of one stable or unstable? Explain. | A cumulonimbus cloud is a cloud of vertical development that can grow up to nearly twice the size of Mount Everest. The air inside cumulonimbus clouds is unstable (when the air inside the cloud becomes increasingly less dense compared to the air outside the cloud), because for a cumulonimbus cloud to form, the air inside the cloud needs to be warmer than the air outside of the cloud. This causes the air to keep rising and condensing until 5 km, when the air becomes stable. Here, the temperature cools down until the temperature of the air inside the cloud equals the temperature of the air outside of the cloud. Now, the air spreads out to the side, forming the hourglass shape of a cumulonimbus cloud. |
| What kinds of clouds are layered? | Stratus clouds are layered. |
| What is precipitation? Name types of precipitation. | Precipitation is any form of water that falls from a cloud to earth's surface. Some forms of precipitation include: Rain and drizzle- both water droplets, drizzle is a lighter form of rain Snow- ice crystals falling down to earth Sleet- frozen raindrops (they freeze as they fall through a layer of cold air Freezing Rain- when the layer of cold air is not thick enough, the supercooled raindrops do not freeze until they hit the ground, where they freeze instantly Hail- begins as a frozen raindrop of a dense clump of ice. It grows by collecting smaller ice particles, cloud droplets, and supercooled raindrops that freeze onto it. Strong updrafts keep hailstones aloft until they become too heavy and fall. The stronger the updrafts, the larger the hailstones can become. |
| Can man influence weather? If so, how? | Humans can influence the weather. One method of making rain is to "seed" a supercooled cloud by dropping frozen pellets of dry ice into it from a plane. Another method is to drop artificial ice nuclei into a cloud, also from a plane. Often, these are tiny silver-iodide crystals, which are a very much like real ice crystals in shape. Once ice crystals form on the artificial ice nuclei, precipitation grows by normal processes. |
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