Final answer:
Hot weather affects the pond by causing changes in the density and freezing of water. Water expands with temperature changes, but is the most dense at 4°C. The phenomenon of water freezing in a pond has multiple effects on the ecosystem.
Step-by-step explanation:
The effect of hot weather on a pond:
In general, objects expand with increasing temperature. However, water is the exception to this rule. Water expands with increasing temperature when it is at temperatures greater than 4°C (40°F). But, it expands with decreasing temperature when it is between +4°C and 0°C (40°F to 32°F). Water is densest at +4°C. One of the striking effects of this phenomenon is the freezing of water in a pond. When the water near the surface cools down to 4°C, it is denser than the remaining water and thus sinks to the bottom. This results in a layer of warmer water near the surface, which eventually cools down and makes the entire pond have a uniform temperature of 4°C. If the surface layer drops below 4°C, it stays near the top, allowing the pond surface to freeze over. The ice on top of the water provides insulation and allows fish and other aquatic life to survive beneath it. It also produces circulation necessary for a healthy pond ecosystem.