Question

Notice that these data were obtained in July. Explain why the amount of stream flow from a glacier would vary each day. Give three examples to support your reasoning.

Short answer

Stream flow varies due to temperature, weather, and precipitation changes.

Step-by-step solution

Understand the Exercise

The question asks why the amount of stream flow from a glacier can vary daily, particularly considering the time of year is July.

Consider Temperature Variations

Daily temperature changes affect glacier melting rates. For example, warmer temperatures during the daytime in July can increase the melting rate, leading to higher stream flows, whereas cooler nighttime temperatures can result in reduced melting and thus lower stream flows.

Examine Weather Conditions

Weather conditions such as sunny or cloudy days impact glacier melt. Sunny days provide more direct sunlight, leading to increased melting compared to cloudy days where less sunlight reaches the glacier surface.

Assess Precipitation Influence

Rain can directly contribute to stream flow by adding water to the glacier and causing increased melting. On days with rainfall, stream flow tends to rise as a result of both additional water and enhanced melt rate due to increased surface temperatures from raindrops.

Key concepts

Temperature Variations

Temperature variations play a significant role in the amount of stream flow generated from glaciers. Each day, as the temperature changes, it directly influences how much a glacier melts. During the daytime in July, temperatures often rise, causing an increase in the melting rate of glaciers. This leads to a higher amount of water flowing in the streams, as the additional melting releases more water from the glacier's ice.
However, temperatures tend to drop during nighttime. These cooler conditions slow down the melting process, which in turn decreases the stream flow from the glaciers. Thus, the daily cycle of temperatures - warmer in the day and cooler at night - creates a rhythm to the glacier's melting and subsequent stream flows.
This repeated cycle of temperature changes throughout the month of July is a key factor in why stream flows from glaciers vary each day.

Weather Conditions

Weather conditions are another critical factor affecting glacier stream flow. Different weather scenarios can either amplify or reduce the amount of glacier melt.
For example, on sunny days, when the sky is clear, more direct sunlight can reach the surface of the glacier. This increases the melting rate, resulting in more water and higher stream flows. In contrast, cloudy days can have a cooling effect, as the cloud cover blocks some of the sunlight. This reduces the amount of warming and subsequently decreases the level of glacial melt and stream flow.

• Sunny days: Increased melting, higher stream flows.
• Cloudy days: Reduced melting, lower stream flows.

The weather conditions on any given day thus play a crucial role in determining how much a glacier melts and the variation in stream flow.

Precipitation Influence

Precipitation, particularly rain, significantly influences stream flow from glaciers. When rain falls directly onto the glacier, it adds more water to the system. But it doesn't just contribute water; it also increases melting.
Raindrops can slightly warm the glacier surface, enhancing the rate of ice melting. This combination results in a noticeable rise in glacier stream flow during and after rainfall events. Conversely, on dry days, there is less additional water input, leading to lower stream flows.

• Rainy days: Added water and increased melting cause higher stream flows.
• Dry days: Lower contributions to the stream, resulting in decreased flow.

Understanding how precipitation affects glacier dynamics is essential to fully grasp the variability in stream flows from glaciers each day.